add: option(warn) stuff: variable names

from spielwiese
fix: tr.532 (jakobkroeger)
new grobcov.lib
add: test for tr.532
Procedures for primariy decomposition of modules added.

Conflicts:
	Singular/LIB/primdecint.lib
fix for tr.538 from spielwiese
fix: primdecint.lib from spielwiese
test for tr.538
new version of grobcov.lib
introduce ASSUME(<level>,<int expr>)
chg: grammar changes for ASSUME
doc: ASSUME
fix: genus (tr.259)
chg: allow chinrem/farey for rational functions