Fixed Win64 build problems with help of Sameh Khamis

* Added VC10 build files, kindly provided by Sameh Khamis
* Fixed several Win64 related bugs (found by Sameh Khamis):
  - define NAN
  - add some necessary casts of size_t to BigInt
  - replaced occurrence of __PRETTY_FUNCTION__ with FUNCTION_NAME that was forgotten in a previous fix
Added special MatLab interface for junction tree algorithm (dai_jtree)
Added Makefile.WINDOWS64, kindly provided by Lin Ming
Oops, forgot a file in the last commit...
Release libDAI 0.3.1
Merged Generalized Loop Correction code kindly provided by Siamak Ravanbakhsh
Fixed GLC::CalcFactorBelief (now uses geometric averaging) and GLC::belief
Fixed bugs in unit test prob_test.cpp
Fixed some more BOOST_CHECK_CLOSE misuse
Fixed division-by-zero issue in pow() which caused problems for GLC+ with sparse factors
Extended SWIG python interface (inspired by Kyle Ellrott): inference is possible in Python now!
Removed conversion script FastInf->libDAI because it is buggy (uses wrong permutation of factor entries)