Failed to load settings file should not prevent TIM from startup

[Angus Yeh]

Thomas reported TIM crash when launching with faulty colorbars.json.

I should make it so that it reports error, but launch with default settings, what needs to be done: - arrow_scales.json - colorbars.json - keymap.json

--- Already done from previous Issue #62 - plot_with_elevation.json - time_history_plot.json

Also should check other plugins, application_state.ini etc.

[Angus Yeh]

Related to Issue #70

[Angus Yeh]

This has been found in a case where the colorbar.json is corrupted (due to closing two TIM instances at the same time?).

It should be fixed so that it tolerate ANY setting files being corrupted, but inform user that some settings were lost because of that.

[Angus Yeh]

Fix issue #68, add safer loading of plot list.

→ <<cset 6a73c43aac3b>>