Some clean-up of memory routines (+ some regression fixes).

Some clean-up of memory routines (+ some regression fixes).

Support (for an obsoleted version of) dmalloc was removed. Removed no
longer used header file (dmalloc.h), that (beside being obsolete) had a
not too permissive copyright notice (only for non-commercial use) that I
doubt is compatible with GPL.

Moved implementation of mstring related routines to a new file
(mstring.c), the same for the miscelaneous files (misc.c). Made sure the
mstring routines are as permissive as possible (add const to char* where
possible).

Empty (ignoring white-spaces or comment) source files removed (cvar.h,
cvar.c, fileIdList.c).

Fixed a regression in metastate test (usymtab.c incorectly dropped a
lookup call, which was in fact needed).