Octave: further whitespace/indentation/style cleanup of octave.cxx

- using: astyle -A10 -s2 -N -p -P -k1
Octave: cleanup/restructure library files

- Restructure runtime code into declarations, function/class definitions,
  and initialisation code
- Rename internal functions/types to follow SWIG_Octave... or SwigOct...
  naming styles
- Style/comment/whitespace cleanups