Now in fteapot you can select any one of the buttons in a modal dialog
with the cursor keys and hit enter and it will be selected.
Fixes#17.
In addition, I clarified that the block attribute options will either set
every cell to bold (say), or unset every cell, or you can cancel to not
actually go through with the block operation.
These changes required adding a custom FLTK dialog, tpt_choose.{h,cxx}.
Along the way, I reflowed fteapot.fl to make it more readable for further
coding.
Finally, there is a small amount of additional prep for color support
that (unfortunately) got mixed in with these changes.
So far, this jst consists of initializing color in curses mode, and making
the display start and end part of intializing and freeing a sheet (so that
it can control allocating the palette, for example, where the data structure
used depends on what kind of display it is.
Next up will be to allocate and destroy the color palette, and set up the
default colors for cells to use (0 for foreground,
TEAPOT_WHITE for background.) The outline beyond that is to allow setting of
the cell colors, then actually display those colors, and finally edit the
palette.