set_universe operation for vset-lib (implemented in listdd32 and listdd64
Fix documentation for ldd options.
allow dot output of symbolic state storage
output group_explored when verbose.
Make listdd64 default vset implementation.
add some logic operators to dm.c/dm.h
allow to clear the matrix, i.e. set every element to 0
listdd make dot static, method also exists in ldd64
move next_count such that it contains real amount of next state calls.
rename flags -> reachable
rename mdd64 to mdd
move node table full check
use constant for unused cache record
support read/write dependencies in pins and all language front-ends
 - rename write to may-write
 - add must-write matrix
 - add universe to vset_prev
 - fix bug in row subsumption (must-write may not subsume copy)
now also dot name of variables.
implement read write separation + support for copy in listdd64
rename vset_listdd program options.