Merge pull request #305 from jadeoneill/master

New Python PLN with forward chainer
PLN won't compile with gcc-4.7

So just stub it out ... it is unused, unmaintained, and it is in the
process of being replaced by a python implementation.
Uncomment debug printfs in MathUTest
Make a weak stab at fixing MathUTest
Merge pull request #308 from linas/build-fixes

Make a stab at fixing MathUTett
Add and/or/ creation and elimination rules. Support multiple outputs. Make the formulas system cleaner
Try supporting various Rules
Rule to convert MemberLinks to InheritanceLinks
Add libserver.so to CMakeLists.txt cogserver_cython to fix #307 & #305 as suggested by IvanLim
Merge pull request #310 from cosmoharrigan/CythonTest

Add libserver.so to CMakeLists.txt cogserver_cython to fix #307 & #305 a...
Start adding a backward chainer
Merge https://github.com/opencog/opencog
Backward chainer. Might not work
Backward chainer kinda works. It should have responsible handling of missing inputs, and rebind all variables (and handle special case Rules)
Add a tacky limitation to hide a bug
Do validity checks in backward chaining too