Initial Archive Handlers visual implementation

The Archive Handlers dialog skeleton now implemented - doesnt do
anything, but demonstrates I can implement the mockup
Archive Handlers visual implementation v2

Code style changes, dialog expansion fixed, terminal checkbuttons
implemented for commands
Removal of previous Archive Handler implementation now its been
approved
Archive Handlers visual implementation v3

Rename General to 'Handler Settings', rename appropriate widgets
Change code style to standard C
Removal of suspicious underscores in default archive type names
Code style - replaced tabs with spaces