in middle of refactoring (merging mlogfilter with mlogmerge).

next steps:
- copy merge part over to mlogfilter and call from logfile_generator.
- rename --labels to --markers and --pos to --marker-pos.
- test well!
updated mloginfo's run() method to take additional arguments parameter.
Merge branch 'develop' into refactor-mlogmerge

Conflicts:
	mtools/mlogfilter/mlogfilter.py
	mtools/util/cmdlinetool.py
still not working. but refactored the merge.
Merge branch 'develop' into refactor-mlogmerge
still working on this.
fixed bug in histogram plots where bucketsize can be smaller than 1.
tools that don't support stdin now exit with error message if stdin input is piped in.
fixed bug where a too small bucketsize leads to invalid width for bin rectangles.
added --restore as an alias for --restart.
LogLine timeformat changes implemented, needs more testing.
added --datetime-format option. utc-local still not working properly.
added support for merge_marker_str
merging implemented in mlogfilter. timezone shift works as well. still problems with iso8601-local.
iso8601-local should now also parse correctly. if datetime is timezone-aware, converting from local to utc also works.
added more tests for datetime parser.
made mlogfilter help texts clearer regarding merging of files.
added more docstrings for mlogfilter.
removed mlogmerge, all its functionality is now in mlogfilter.
added file size to LogFile class.
added binary search for mlogfilter --from for single files, no stdin.