Since `parse.gperf` was added long ago, the ability to run Tux Paint
with "--fullscreen" command-line, or simply "fullscreen" in the
config. file, no longer exists.
It must be `--fullscreen=yes` (or `--fullscreen=native` as an
alternative to `--fullscreen=yes --native`). It can also accept
`--fullscreen=no` as an alternative to `--windowed`.
Updating the following places
* BASH tab completion
* `tuxpaint --help` output
* FAQ
h/t Karl for reporting
Closes https://sourceforge.net/p/tuxpaint/bugs/289/
...mostly in terms of modularizing how various file
and directory (folder) paths are shown (for consistency in
both name and styling); add some missing paths (e.g., where
does Tux Paint save drawings on Haiku?)
