make a note about the wikipedia definition of data compression rate
fix the output of the compression_time_vs_chunk_size.py
drop caches and sync
sync after write and include in timing
make reuse of the progressbar
fix import
reuse the progressmeter again
use a different prefix for the bloscpack-tempdir
Merge branch 'enhance/benchmarks'

* enhance/benchmarks:
  use a different prefix for the bloscpack-tempdir
  reuse the progressmeter again
  fix import
  make reuse of the progressbar
  sync after write and include in timing
  drop caches and sync
  fix the output of the compression_time_vs_chunk_size.py
  make a note about the wikipedia definition of data compression rate