Changes to PYTHONPATH so it includes VERSION

- accept empty string from focus_get
- map coords() return value through getdouble and splitlist

- move compile() inside try-except
- add code so you can do "python pdb.py <script> <arg> ..." to debug <script>

(then f may be None).

- Better staggering of windows
- Windows have zoombox by default, and zooming works
- DrawControls->UpdateControls
- Better scrollbar show/hide

underscores.

"make libinstall" no longer implies "make sharedinstall".
"make altinstall" and "make altbininstall" install the python binary
with a version number, for tentative installations (this does not
install the include files or man page).

Forget about the trick to create directories through dependencies --
it's impossible to get it right in the light of parallellizing Make
implementations and the inability to specify dependencies between
directories (because creating the subdirectory modifies the parent).