Change and expand API
Use new colors API
make default current line color very light
first cut at highlighting current line
And now a very pale yellow
cursor_moved now correct and not wasting time, also places that call it
change name of a method
Tidy up API arguments
Clean up API commentary and add all def's
Add get_ and set_cursor methods
Add call to get_cursor in test
Rename internal methods with leading underscore, move stuff around
Rename internal method with leading underscore
clean up api and commentary
rename internal method with underscore
Add method folio_string and folio_format, and lots of error checking
Update folio text when page data available
Various renamings and shufflings