we can load parameter files

we can load parameter files
Mussagl now as several ways to load an analysis.
There are now two command-line arguments, run-analysis and view-analysis
which will load a parameter file and an analysis directory respectively.

The menu items in mussagl are also connected to slots in PathScene to
handle loading.

When something is loaded PathScene::updateAnalysis will (if the
analysis actually has some contents) run the analysis.

However there's some bug where the loading the previously saved analysis
is choaking on some assertion.