Move database, depth choice

A file ~/.bcmoves may be used to avoid repeating mistakes:
it contains a record of board configurations, a count of games
they occured in, and the differences of winning and loosing
the game. This cured some of those really annoying, trivial
winning strategies against the AI.

A new algorithm for determining how many turns lookahead should
be used. Seems to work quite nice (by now it is even possible to
win against the simple levels, without being bored too much).
bugfix in normalization
Correct spelling mistakes, fix README improve make install
Typo correction
Merge branch 'devel' into ai_tuning

Conflicts:
	Makefile
	baghchal.c
Type correction in Makefile
Typo fix
Typo fix
Install cleanup, use the install command
Add license headers
Merge branch 'ai_tuning' into gui

Conflicts:
	tkchal.py