JOAL Fixes: GlueGen, OpenAL Header, Added scripts/tests.sh,

- OpenAL Header
  - Unique declaration in al-types.h and alc-types.h, remove duplicates in al.h and alc.h
  - Use ALproc and ALCproc for opaque pointer return values

- GlueGen Fixes
  - Remove duplicates in extension classes ALExt and ALExtConstants
  - Push all common configurations to joal-common.cfg
  - Complete ArgumentIsString for ALC methods

- Added scripts/tests.sh for convenient manual testing of single unit test

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