GCC 4.8.3 warned that "typedef 'Scalar' locally defined but not used"
libMeshEnums namespace for backward compatibility
Merge pull request #407 from libMesh/libMeshEnums_restore

libMeshEnums namespace for backward compatibility
Adding a .mailmap file to the top level of the repo

This file helps avoid duplicate/redundant entries in the output of
'git shortlog -s'
Enable explicit instantiation of CodeTree in fpoptimizer.cc (#397)
Rebuild fpoptimizer.cc uncompressed (#397)
Start recursive tree-based diff algorithm (#397)
Starting to implement differentiation rules (#397)
Implement remaining opcodes using operator overloading (#397)
Rm old AutoDiff, add d/dx(plog) (#397)
Use pimpl idiom to encapsulate AD implemntation (#397)
Fix FParser Makefile (#397)
Modify tests/Makefile.am add unit test (#397)
Fix test program compilation with/without fparser debugging (#397)
Always build and link FPoptimizer, but only use it when enabled (#397)
Rebuild fpoptimizer.cc (#397)
run bootstrap (#397)