Minor adjustment to UI

Got rid of that unsightly border and moved the title onto the top row of the termbox.
Removed a bunch of unnecessary draw calls
Added ability to draw coloured text in tbutils
Updated new UI design to use tbutils
Broken up mega drawAll() function
Fixed extra line in end of stack message
App name and app version are now pulled from cli context
Updated version
Refreshed stack index UI

Shows progress as a percentage, looks similar to header
Oh so minor change to UI's header bar
Improved error message when parsing of TOML file fails
No more panics when no flashcards are found
Fixed incorrect reference to JSON in usage string
Added usage string
Finalised version string
Merge branch 'v0.3.1'