This is just a simple code refactor, moving and function renaming to
remove the %extend code out of the parser into its own file now
that it isn't just used in the parser.
fixed language symbol table nested classes name separator, test added
fixed %feature "flatnested" working with %extend
fixed Swig_offset_string for empty string
added simple template to save/restore values in current scope (readability reasons)
Error checking for this combination implemented as well as correcting
Octave
Also refactor, replacing CPlusPlusOut variable with cparse_cplusplusout
for an implementation which more closely resembles cparse_cplusplus which
is also required in both .c and .cxx files.
