Delete comments and add some description text.
Rename 'yaf_mapworld_type' variable to 'bg_mapping_type'
Expand checkSceneLights() function.
Delete unused 'use_color_management' from presets.
Change 'yaf_mapworld_type' variable  name  to 'bg_mapping_type'
Change some old project names.
Re-define some style code.
Uncomment UV layers code: now this feature is work ( new more test..)
Change some panel names ( delete old project references..)
Applied mapping variable change name.
Hide some panels for 'texture background' mode.
Change  some variable names:
    -'tex_in' variable  for more explicit 'mapName'.
    - diffRoot to 'maskRoot' for texture mask slot in Blend material.
    - 'diff_layer' to 'mask_layer' in Blend material.
Refine code for 'negative' and 'noRGB' variables.
Change some style code.