CVS griph: * add variable filters

[FVWM CVS]

CVSROOT:        /home/cvs/fvwm
Module name:    fvwm
Changes by:     griph   06/07/14 17:30:03

Modified files:
        .              : ChangeLog NEWS 
        fvwm           : expand.c fvwm.1.in 
        libs           : Strings.c Strings.h 

Log message:
* add variable filters
* make backslash escape character within $[...] expressions