Clang False Positive Test Fixes

This addresses the issues discussed in #152 with multiple parsers and the integration test.  Python does not support module unloading.  Even when you remove an entry from `sys.modues` and make sure it has zero references, the dynamic library may still be loaded in memory.  

This PR avoids tricks the interpreter by building and installing the dynamic libraries in parser name dependent locations (eg 'build-clang'). Parser order or inclusion should no longer matter.

Note that the commented out call to `clang_fix_onlyin` in `autodescribe.py` will need to be uncommitted to restore a fully working code base.

@girving, I think this one is for you!