Feature: reopen previous fits on startup
Add thread for opening fits on startup, which allows us of wait dialog

Wait dialog doesn't actually move as the GUI thread is locked when opening the fits, but at least it shows that -something- is happening.
Improves on fit loading on startup by only calculating the last fit that is opened.

Issue with FittingView.MakeSnapshot() need an exception catch.
Merge branch 'issue-102', resolves #102