Also add the priority parameter, which was missing.

Updated APIs to support arbitrary deadlines. Added macros for implicit
deadlines.

Note: Had to tweak Makefile to support gcc version >= 4.6 (moved -lrt to the
end of the link command).

Use the kernel's notion of fixed priorities.
Also, add some clarifying comments to the
task setup wrappers.

      PCP was only used for DPCP before

tests: add some basic tests for PCP under P-FP

      dissertation (branch bbb-diss)

      I took the unchanged code but removed references
      to OMLP which was and is not implemented

tests: changed so that they work for P-FP

The timing functions are quite handy when building benchmark tasks.
Avoid copy&paste reuse by making them available via the library.

We want the positive loop length, not the negative, to prevent jobs
from overruning their budget.

Using cputime() is much more accurate than the old delay loop
auto-configuration. There is no good reason to keep it around.

Still need to figure out what to do with the period is less than the
exec_cost (or budget).

rtspin produces prettier schedules if it transitions to non-real-time
mode before terminating.