Added CLI support for the backgrounder tool

Similarly to the MultiTrack tool, if user does not provide any command
line options, it runs with GUI. If user provides all required options
(VIDEO FILE and OUTPUT FILE) then it runs in the command line with
provided options. In case of providing just one parameter - it displays
its usage help.
Removed unnecessary includes
CLI support

usage: Backgrounder VIDEO_FILE OUTPUT_FILE [average|mode|median]

third parameter is optional (default action is "average").
Merge branch 'master' of https://github.com/lejlot/biotrack into lejlot-master
Half-way updated to pcl-1.7 and qt5

It looks like pcl-1.7 has API changes that affect us,
and pcl-1.6 has macro's that do not play nice with
qt5's moc. So we're stuck at pcl-1.6 and qt4.

The committed changes are backwards-compatible with
qt4 (with warnings about the new Qt5 option "widgets")
but should make us slightly less unprepared for the
upgrade when it arrives.
Tweeked Backgrounder

Delayed object creation in main.cpp so we don't have to delete
the object if we're not using the average method

Added printf's in BackgroundCalculatorMode.cpp so we know it's
not frozen. Should be more useful in batch mode.