Started implementing new debug_level meaning and added automatic trace.

Not sure if automatic trace is a good idea
+ Always up-to-date trace
+ Toggle debug_level >= TRACE
+ Automatic trace for every debugmsg
- Exists only for c99 (kernel module would lose the possibility to print traces...)
- can only be printed before the actual message (because of new-line message of the printed message), cluttering the output.
testing new macros TRACEIN() and TRACEOUT
make TRACE-ing depend on debug_level
forgot to remove one out-commented line
with the optional macro parameter for TRACEIN(), this should now also work in the kernel and no need anymore to redefine the _TRACE() macro
added traceoutput to debugmsg as well as file and line number
Fixed #14, #17: implemented debugmsg convention.
- set TRACE to 99, this means all test scripts continue to work for now
- not all DEBUGMSG are converted yet