Now all parts of spreadsheet respond to the -F <fontsize> command
line argument in fteapot, and row heights are computed in terms of
the resulting character size.
There is a new menu option for setting row heights in fteapot.
Documentation is updated, and keybindings are made more uniform between
teapot and fteapot and more fully documented.
Resolves#57.
This update adds a command-line option, which only affects fteapot,
to set the overall font size in pixels.
It also allows the row heights to be set, in units of 1/ROWHEIGHT_DENOMINATOR
rows (although only the integer part of the row height is relevant in
the terminal spreadsheet).
Still needs a menu option for row heights in fteapot and documentation.
