sylvan: update to MDD branch
vset: implemented multi-core LDD support (via Sylvan)
Fixed test suite for mu-calculus layer, added tests, fixed bugs in mu-calculus layer.
Added generated mucalc lexer and parser to .gitignore
- Added parallel attractor function for spgsolver.
- Reorganised files for spgsolver.
- Solved bignum bug in spgsolver.
- Fixed reading and writing of symbolic parity games in spgsolver.
- Lace initialisation in spgsolver.
- Changed output of symbolic tools and spgsolver.
- Debug macros.
- Read and write dependencies in pins2pins-mucalc.
- More uniform screen output in spgsolver.
Added multi-process environment for non thread-safe language modules in the
symbolic reachability tool.
Fixed a bug in PINS with automatic projecting and expanding vectors.
The group information was not copied correctly.
Fixing multi-process symbolic tool for read/write separation and copy values.
Fixing loading of symbolic parity games.
typo in pins.c
fix header when printing combined matrix
count short vectors in group_explored
only over approximate W to + when domain separates rw but not copy
clean up print dm
remove r2w functions and introduce expand and project matrix.
add option --no-matrix.

Conflicts:
	src/pins2lts-sym/pins2lts-sym.c
fix null pointers when printing matrices with -v (verbose) option
print extra info about state labeling.
extend vset interface with vset_join
rename + move element of op cache