Changed qtlab_shell script so that it uses the current working directory and is callable on import.

When calling the run function it correctly finds the init files but failes on the import statements as the qtlab/source folder has not been added to the path.
Found a recursive loop in the import statements of the qtgnuplot.py while fixing import statements

Fixed it by replacing plot. (in the qtgnuplot) with _qtgnuplot, this has the potential to break things but I have no clue how this worked in the first place.
Merge branch 'master' of https://github.com/AdriaanRol/qtlab-fork

Conflicts:
	qtlab/source/lib/config.py