Initial attempt at libopenjpeg2 support

OpenJPEG 2 has a new pkg-config name and API.

- Update to find openjpeg 2 and provide V1/v2 macros
- Update JPEG2000Stream to use new API depending on openjpeg v1/v2 macros
- OpenJPEG 2.1 changed the API so provide a version macro to make it easier
  to handle the the 2.1 change and any future changes.
- Move openjpeg.h into the .cc file
3 files changed