core/crc: Fix the 64 bits implementation

We used 1ULL at one place and not the other ... at the same time,
we now use (uintXX_t) so that the proper type is used each time.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
doc: Fix typo in Doxyfile.core.in causing sources to be ignored

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Implemented and tested ringbuffer-based logger, rebased, use via show alarms
Most of the changes suggested by Holger