fix: doc for tasks.lib/resources.lib/parallel.lib

Conflicts:
	Singular/LIB/oldpolymake.lib
chg: error message for coeff: integer + parameter
chg: rCharstr is now a wrapper for r->cf->cfCoeffString

fixes also: charstr for integer,2,3
fix: more charstr stuff (tr.237)
add: tests for tr.237 (charstr)
 fix: more charstr stuff (tr.237): Z/(n^m)