STLplus C++ library collection SVN stlplus3

Slight mod to comparison logic

Made the internals of subprocess and async_subprocess protected so
they can be accessed by subclasses

added method for testing the presence of an environment variable in env_vector

updating inline with header

Added test for the environment vector initialising correctly

Moved declaration of environ into more sensible place

Internal access function in env_vector made private

updated in line with header

rearranged for readability

removed unnecessary dependency