(svn r12060) -Fix: do not clear tiles when the town won't be able to build any buildings anyway
-Fix: allow building 2x2 building on slopes if not explicitly forbidden
-Fix: it was possible to build 2x1 and 1x2 buildings on slopes even if it was not allowed

Makefile*
bin/*
!bin/data/chars.grf
!bin/data/openttdd.grf
!bin/data/openttdw.grf
!bin/data/opntitle.grf
!bin/scenario/README
!bin/scripts*
config.*
objs/*
src/rev.cpp