SVGHMI: Fixes UI lifecycle problems

Was sometime showing HMI tree of previously closed project : no more module globals to store hmi tree.
C++ dead object exceptions happened when re-opening SVGHMI UI or building after close of UI.

*.pyc
**/__pycache__
.vscode
**/build/**
*.class
**/.svghmithumbs/**
**/my_*.der
**/my_*.pem
tests/tools/Docker/requirements.txt