Signals and ipc and stuff

- Cleaned up signal handling. Should be fewer zombies. master job might produce a zombie, since we are not guaranteed that it is the same process that creates and kills the master process, and I'm reluctant to mess around with signal handlers and actions inside apache, assuming apache uses them.
- Added multisampling (enabled on application-by-application basis via API in IPCGLController)
- Added support and use of a logging callback in the controller hierarchy. The idea is to let the job decide on which specific logging system to use, and not let tinia impose something.
- Added new glx context creation code, handles more cases, supports profiles and debug contexts, should be more robust as well.
- Added support for masterjob to list rendering devices and installed tinia applications.
- Imporved the UX of tinia poke.