#83 Improve interface between main dialog and profile checker

[Hal Engel]

From Craig Ringer - ringerc

If the user wants to run the profile checker they should be given an open dialog that pre-selects the last saved profile. The current approach is somewhat confusing, especially since "profile checker" is enabled before a profile has been saved / before any valid measurement data has been set.

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The reason that the profile checker button is not grayed is because even though a user may not have created a profile the profile checker can be used in a standalone mode and the user can enter a profile file name and measurement file name (and reference file name if it is opened from the camera/scanner profiler) once the profile checker has been opened. If the user has created a profile on the current tab then the profile checker will by default open the last profile created by the user on that tab (IE. monitor or camera/scanner tab).

I have noticed that it does pop up some warning dialogs asking for a profile name when it is opened this way. That definitely needs to be corrected. And there are perhaps other things that can make how this operates clearer to users.