Tests: add opc-ua encrypted test

Merged changes from default

SVGHMI: update generated XSLT

SVGHMI: Update svghmi_references example to demonstrate use of Assign widget.

SVGHMI: Add Assign widget, doing multiple assignments on click.

SVGHMI: add visible feedback to Jump widget when clicked/touched

SVGHMI: add support for "reference" and "frame" rectangles to spread-out ovelapping elements.

When HMI become complicated, designer needs to spread-out ovelapping elements
in order to unclutter drawing and facilitate maintenance.

SVGHMI: remove intermediate "updates" Map and apply_updates()

It was used initially to decouple DOM updates from reception of data through
websocket, but now since all widget SHOULD use animate() to modify DOM, and
dispatch() only change internal state, apply_update is unnecessary.

SVGHMI: cosmetic fix in js

SVGHMI: do not discard out-of-page elements inside widgets that are ovelapping pages.

SVGHMI: update generated XSLT

OPCUA: cosmetic fixes

CLI: poll runtime log and output new entries to stdout.

CLI: when using --keep, do not disconnect before being interrupted

Runtime: work around 1s delay added when using twisted reactor's callLater.

Since wxPython4, using wxReactor from non-main thread was producing
exceptions in wxWidget's C++ code. Then reactor.run() was called from
main thread, and runtime's worker was delegating calls to reactor
with callLater(0, callable).

While this worked perfectly with wxReactor, it did introduce an unexplained
1 second delay to each worker call when using nomal linux reactors
(i.e. without wxPython). As a workaround reactor runs in a thread when using
twisted without wxPython

tests: opcua_client test project is not meant to be encrypted.

SVGHMI: update generated XSLT files

Merged changes from default

SVGHMI: ensures that PLC sends only fresh data to HMI, even right after variable being subscribed.

OPC-UA: add logging to help user to understang what went wrong when connecting.

OPC-UA: fix LDFLAG, missing OpenSSL's -lcrypto

open62541 is linked staticaly, therefore shared object dependencies have to be given explicitely.

tests: missing SSL support in open62541 build parameters

Merge changes from default branch

merge

Merge pull request #5 from vitw/wxPython4

update installation instructions

docs: add additional dependencies to installation instructions

update installation instructions

SVGHMI: fix svghmi_jumps example's SVG file (viewport was misplaced)

SVGHMI: rework the way cached values are applied to widgets when fresh data is missing.

SVGHMI: re-arrange Animate and data Dispath code paths.

SVGHMI: add an exemple that demonstrate use of Jump widget in different use cases.

SVGHMI: refactor an factorize widget dispatch() method calling

SVGHMI: fix ToggleButton not always reflecting current state

IDE: fix exception transfering or reconnecting after tracing variables

SVGHMI: Add predefined assignments to jump widget to notify PLC or other widgets about jump.

SVGHMI: continue rework of Jump widget to cope with Enable Expressions.

Questioning widget's activity and disability all together.
Now active/inactive/disable masquarade is all managed in widgets_common.
Propagated changes to widget already using activity (buttons)

SVGHMI: rework Jump widget to cope with Enable Expressions.

Relative jumps are not disabled implicitely anymore when pointed HMI_NODE is 0.
Also, "activable()" implementation was enhanced to make it optional.

SVGHMI: add support for "enable expressions" with arbitrary variable name assignment.

HMI tree paths can be prefixed with a variable name "@name=/MY/HMI/VAR"
Widget declarations can end with a "#" followed by a JS expression that refers to name given to variables.
Widget is disabled if expression's result is false.

Commit includes some more-or-less related generated code refactoring, that should simplify extending widget's variables attributes.

SVGHMI: preliminary implementation of a general enable bit for all widgets, using "#" at the end of widget declaration, and a "disabled" element that becomes visible instead of widget when disabled.

SVGHMI: rename veriables in parse_labels.ysl2 for better readability

OPC-US client: add support for x509 and user+password authentication.

Commit for backup not including tests since encrypted OPC-UA test are still not valid.

IDE: fix wxPython 3->4 API change leading to exception in type selection menu in CodeFileEditor

OPC-UA, IDE: add CTN parameters to support OPC-UA encryption and authentication.

xmlclass had to be enhanced to support elements with no content in xsd:choice

IDE: Fix tooltip not being shown anymore on any toolbars since switch to wxPython4.

Cleanup and update version.py

IDE: Fixed About dialog exception on Windows, and typo in about dialog's content.

runtime: fix bugs introduced in previous commit, and refactor some code

Runtime: wx.app.mainLoop and twisted reactor now share main thread with runtime.Worker.

This fixes exception when invoking python interactive shell from Runtime's tray
icon right-click menu.

Probably a consequence of wxPython upgrade, together with initial bad idea to
move wx.app.mainloop in non-main thread.

Remove useless assignment

SVGHMI: update generated XSLT

tests: fix load_and_build_tests.pytest

Leftover import from previously commented-out tests. Commented out as well.

Merge changes from default in wxPython4

SVGHMI: add support for multiline widget declaration using svg:desc.

Declaration started in inkscape:label and interupted by a '\' can be continued in the description field.
After an empty line, the rest of the description field is left for description text.

Runtime: Fix PLC python thread crash in case of exception in PostStart customization hook.

IDE+Runtime: fix exception when reconnecting with non-empty trace/force list.

Sometimes, remote call to SetTraceVariableList returned None just after reconnecting:
- changed caller to accept None (in case of connection problem)
- changer SetTraceVariable list to return 4 (DEBUG_SUSPENDED) if debug is suspended

Runtime: Retain: fix missuse of static classifier leading to ever increasing offset.

IDE: one more consequence of wxPython's 3 to 4 version bump

IDE+runtime: Fix .ico generation

IDE, SVGHMI: Workaround Snap package not launching Inskape, POEdit or Chromium directly, producing lot of output in Incskape CLI, and messing with TMPDIR

IDE: wxPython4 consequences : wx.OPEN -> wx.FD_OPEN