rm-logfiles

Changed treatment of during type inference internally generated type
variables.

1. They are renamed to 'a, 'b, 'c etc away from a given set of used names.
2. They are either frozen (turned into TFrees) or left schematic (TVars)
depending on a parameter. In goals they are frozen, for instantiations they
are left schematic.

#! /bin/sh
#rm-logfiles: remove useless files from subdirectories
rm log */make*.log */make*.log.gz
rm */test
find . -name '.*.thy.ML' -print -exec rm {} \;