SVGHMI: strip useless placeholder bitmap of HMI:Image in resulting xhtml

SVGHMI: fix build exception when static file directory is missing

Various unrelated code quality enhancements and fixes with no effect on execution.

MQTT: allow publish and subscribe from user python code.

python runtime: fix exception when transfering files with identical content.

SVGHMI: add static file serving feature.

Added two buttons to add and remove files.
Files are stored in project inside a directory named "static",
itself located in svghmi CTN instance files. Exemple :
exemples/svghmi_csv_json_img_table/svghmi_0@svghmi/static/
Files are transfered as "extra_files", but with a prefix
added to their name to avoid conflics.

Make Input widget actionable. Includes example from kraskrom@github.

Merge remote-tracking branch 'origin/python3' into python3

Update README.md

SVGHMI: fix inverted behavior of SuppressBrowserOutput.

Tests: matiec version bump

Update requirements and add minimal non-frozen requirements for developer setup

Merge remote-tracking branch 'origin/python3' into python3

runtime: make standard output more silent.

SVGHMI: Make Back widget activable. (#52)

PLC build: prevent duplicated CFLAGS for PLC C files.

IDE: more wxPython4 related fixes. AUI Update crash on exit + PLCOpenEditor Save exception.

merge

py_ext: CSV Writer output FB interface: ERROR and RESULT are valid when ACK is TRUE.

+ updated svghmi_csv_json_img_table accordingly

IDE: fix exception when changing or resizing comments in FBD

PLCOpen editor: fix exception when using file open dialog

Consequence of wxPython 3 to 4 API changes.

IDE: Fix wrong red wire coloring in FBD, this time for good.

py_ext: fix CSV update happening only once.

py_ext: rework logic CSV reader FB output refresh logic.

Saving with CSV write FB now triggers CSV read FBs to refresh outputs immediately.

py_ext: fix CSV Writer

fix POU logic :
- SAVE is a BOOL
- invocation of py_eval on rising edge of SAVE
- remove save python argument

fix python:
- use no encoding for file open (python2)
- re-use detected dialect if any
- use no "rt+" and truncate since no need to re-sniff dialect for output file
- return "OK" instead of "#SUCCESS", preventing POU logic to ACK result
- support creating new line if writing just after last line
- support appending data on short rows

fix example:
- use a HMI:Button to trigger CSV write instead of HMI:Input +1
- reload CSVs on on each new CSV opened in file browser
- add display of CSV write output

IDE: Fix wrong red wire coloring in FBD

C runtime: move generated erpc interface in separate "service" directory

IDE: Fix PLCOpenEditor (wxPython4 menus) and drop broken PDF doc support.

Extend HMI:JsonTable, create Edit CSV POU, create example, add some doc (#41)

* Extend Jsontable widget, create Edit CSV POU, create example for both

* Add doc for HMI:Image and HMI:JsonTable

* Expand example to include HMI:Image

Tests: matiec version bump for GH workflow