Changed to using boost as a static lib
Added imgexputil file as a place to store extra-api functions that are useful for the user.
Moved all the imgexp implementations to imgexp.cpp file.
Added a BuildExpressionTree utility function that will build an expression tree from a map of points and PixelMatches.
Put the namespace definitions behind a #define to get around visual studio indenting namespaces.
Ported all the tests from CppUnit to Gtest.