Compilers other than GCC and MSVC++

[Kristofer Spinka]

The two include files:

lib/convert.h
lib/defs.h

contain defines that only seem to support GCC and MSVC++. 
 I think most Unix compilers/platform headers will be able 
to interpret the GCC version of the defines in these 
headers.

I would like to recommend that the __GNUC__ become the 
default in an "#else" block instead of a throwing a 
compiler error.

   /kristofer