Move script command generation to single-include header ScriptCommandModule.h to be included in one cpp file per project

MexIncludes/PyIncludes are now specifically include python/matlab headers ScriptIncludes.h is more general

- Added ./ directory to all project includes to avoid needing ../ before inter-project headers

- Added literal_string for simply storing larger strings (msvc has problems above 512 bytes)
- Added '.' to usage string
- More efficient gen_sequence for longer integer_sequences

- Usage function uses const_string where possible for compile-time concatenation