Patch: global event sets instead one per thread for multithreading ve…

…rsion: causing problems in KNL

New release: some changes in the API, added subregions, some bugs fix…

…ed, better documentation, added tests and CI, added CSV format (optional) and cleaner code.

Fixed bugs for single thread version

Better performance: no critical section when flushing. Cache flushing…

… also between swapping counters

Bug fixed: cache flushing in all cores

Added new macros for measuring events within a loop in order to avoid…

… the overhead of the initialization

v0.3.1, quick fix

Released v0.3, implementing properly sampling

Quickfix: removed PW_SAMPLING feature for the moment