Update to building with MPIDE 20140821 and new Arduino-Makefile.
Use MIN/MAX macros instead of std::min/max for portability.

The latest MPIDE build tools don't have this std library.
Update compiler flags to work with latest MPIDE.
Update to latest Arduino-Makefile and use standard Make variable names.

Turns out CPP == the C pre-processor and CXX == C++.
Update Arduino-Makefile to build with latest MPIDE.
Compile tests with clang for its awesome warnings.
Clean up coverage targets and add diffcover.
Merge branch '264-2014-08-mpide' into next
Use proper build options when running 'fab <platform> flash'.