Change links' type in app_dev_guide
refs #867
Added switch_and_groups
refs #867
Added signal_handlers
refs #867
Adde module references
refs #867
Renamed widgets_to usefule_widgets
Added descriptions to widgets
refs #867
Reorganised toctree
refs #867
additional doc extension:
fix pisak.symboler.rst
change theme
add logo
change chapter styling
change author order
add paint module
refs #867
remove not needed toctree from application.rst
refs #867
extend architecure description
refs #867
work on readability
refs #867
add section of PISAK's objects properties - blank for now
refs #867
Merge branch 'master' into doc-guides