implemented progress bar for mplotqueries.

also removed "other" group if it is empty after limiting.
added one more whitespace per line to trigger markdown code block.
minimum width for range plots, and label only once.
Merge branch 'feature-106-progressbar' into develop

Conflicts:
	mtools/mplotqueries/mplotqueries.py
merged progress bar features.
added dateutil dependency to setup.py.
fixed bug where the progress bar assumed that a certain line has a datetime. That's not always the case.
progress bar bug, line didn't clear always.
mplotqueries bug with empty files fixed.
fixed same progress bar bug as mplotqueries with mloginfo --distinct.
fixed same progress bar bug as mplotqueries with mloginfo --distinct.
Merge branch 'bugfix-109-empty' into develop
fixed a number of bugs related to empty files and mlogfilter and using pipe syntax to call mlogfilter. Fixed #103.
Title does not include <stdin> anymore, and added a new option --title to overwrite the default. Fixes #103. Fixes #112.
fixed --logscale as a parameter, which wasn't currently working.
added proper y axis labels to range type plots.