Trivial: more test details that shouldn't matter.

These details shouldn't have any effect on the test, but if there is a problem (which is the point of a test), their absence might not be detected.
More debug information about NFA->DFA conversion.
Rename debugging() -> tesla_debugging().

Avoid possible namespace collisions when linking libtesla into user applications.
Make event output conditional on TESLA_DEBUG.

From now on, to see TESLA events displayed on the console like this:
[CALE] example_syacall 0x7fff573805c8 0 0
[CALE] hold 0x108887260
[RETE] hold 0x108887260
[RETE] example_syacall 0x7fff573805c8 0 0 0

one must set the TESLA_DEBUG environment variable to match 'tesla.events'.