IDE: fix exception when removing a file in Project Files manager.

Update README.md

Tests: fix OPC-UA test when run from repo.

project_files directory isn't commited because empty,
test fails if project_files is missing.

OPC-UA: better logging in case of failure at init

Tests: version bump open62541 v1.3.2 -> v1.3.3 for github CI workflow.

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