Adding radio buttons to fileselector

 - add to egui_layout JSON
 - add to egui_layout_c.src
Gui Builder: add Export mode to Project menu
main: refactoring to use getopt
fix parser issue with filename
main fix in file path resolving
cmake: refactoring
layout: remove <font_size> tag from factory
change eolian 'find_by_name' to 'get_by_name'
Update according to Eolian changes
ResMan: make HOME default path for fileselector
PropView: fix UNUSED warning
fix issue with namespace - property delimeter
CallbackView: reverse events list (fix with scrollable hoversel)
put empty value for hoversel, when object not selected
Merge branch 'develop'

  - fetch default properties from widget
  - coloration of default properties
  - add export menu into Gui
  - refactoring to use getopt
Explicitly delete window's inline image

  Don't know why it appeared suddenly... need to watch after
small refactoring of editor_init()/shutdown()
Merge branch 'develop'
ffi_eo_do_get: handle default ENUMs in a proper way
eo_class_mro_get(): avoid duplicate classes in MRO list