Merge pull request #1 from JohnLangford/master

Catch up
Normalizing makefiles - using COMPILER consistently, passing flags in etc.
Specify compiler in top-level Makefile
Fixed an oops in clean
Use clang++ if found otherwise use g++
Moved the arch selection
Fixed inline issue
Merge pull request #2 from JohnLangford/master

Pull req#2
Merge pull request #3 from martinthomas/make_clang

Make clang
Add -j8 to Makefile
.
Merge remote-tracking branch 'origin/master' into make_clang
Added DNDEBUG back
Merge pull request #4 from martinthomas/master

Added DNDEBUG back
Merge pull request #241 from martinthomas/make_clang

Make clang the preferred compiler