* rename src directory to allocbench
* make global variable names UPPERCASE
* format a lot of code using yapf
* use lowercase ld_preload and ld_library_path as Allocator members
* name expected Errors 'err' and don't raise a new Exception
* disable some pylint messages

Thanks to Matthew Parkinson
see: https://github.com/daanx/mimalloc-bench/pull/14

The barrier prevents worker thread from doing work before the main thread
starts the timing. This behaviour was mentioned in the paper:
Mostly Lock-Free Malloc by Dave Dice, Alex Garthwaite

Make scans the project directory for Makefiles and executes them.
The targets should be build by the new targets/Makefile.
All included Makefiles are now "quiet" by default.

each benchmark has its own Makefile which must put it's binaries into
OBJDIR which is added to the PATH during execution.