Update Graphs.m2

This is the all new Graphs package.
Update GraphicalModels.m2

Modified trekSeparation to stop monkeying around *inside* a Digraph.  Fixed a type in the example of directedEdgesMatrix documentation.
Update Posets.m2

Lots of small changes.
Update Graphs.m2

Modified addEdges to not break NautyGraphs.
Update Graphs.m2

Adjust for the vertices symbol in SimplicialComplexes.
fix a Makefile
Merge branch 'master' of github.com:Macaulay2/M2

Conflicts:
	M2/libraries/pari/Makefile.in
update INSTALL for Scientific Linux
Merge branch 'master' of github.com:DanGrayson/M2

Conflicts:
	M2/BUILD/dan/Makefile.scientific
	M2/INSTALL
my makefile
Merge branch 'master' of github.com:Macaulay2/M2
update change-log
update NormalToricVarieties.m2

new file provided by Greg Smith
Merge branch 'master' of github.com:Macaulay2/M2
undo a change we did to the 4ti2 configure script
Merge branch 'linalg' of github.com:DanGrayson/M2 into linalg
Added Divisor.m2 for consideration in Macaulay2
Merge remote-tracking branch 'upstream/pull/159'

Conflicts:
	M2/Macaulay2/packages/=distributed-packages
add new package Divisor to the list of changes
Minor changes to Divisor.m2