added missing files from last commit.
BREAKING CHANGE!
- reworked sampler uniform handling in program object
- prior: use of program::uniform_1i to set texture unit (or uniform convenience template)
- now: use program::uniform_sampler to set texture unit or program::uniform_sampler_handle to set resident handle
- uniform_image changed accordingly
- adapted examples and utilities to the change
- run in debug mode to find faulty program::uniform calls