Experiment selection

[bboudaoud-nv]

This branch adds support for selecting the experiment from an experimentList when in developer mode.

The approach is a bit complicated, but should make things easier for users. The only config changes are in the startup config file, which now supports 2 new fields (and drops support for "direct" configuration file specification):

• A defaultExperiment which sets up the files to use as defaults for experiment(s) if none are provided, and specifies the only experiment if no experimentList is provided
• An experimentList which provides a list of (named) experiments as deviations from the defaultExperiment provided above

The defaultExperiment and experimentList entries contain the same file fields that used to exist at the top level of the startup config, namely:

• experimentConfigFilename
• userConfigFilename
• userStatusFilename
• keymapConfigFilename
• systemConfigFilename
• resultsDirPath

In addition to these fields, entries in the experimentList also require a name field to be provided to make them unique.

When run in developer mode FPSci allows the developer to select from an additional user menu drop-down list of experiments. Otherwise the app (currently) always runs the first experiment in the experimentList (or the defaultExperiment if no/an empty experimentList is provided).

Merging this PR closes #261

[jspjutNV]

This is already looking pretty good, but I think it's got some more improvements that we should make. I'm going to schedule this for the February release.

[bboudaoud-nv]

Changes are welcome, there are still some occasional bugs occurring around what seems to be GApp widget management (specifically event processing) when we re-initialize the experiment. We might want to consider an alternate approach to cleaning up state before we initialize the experiment.