Automatically load image alignment if it exists

[celefthe]

When previewing images that have already been aligned, the GUI currently uses the current alignment (i.e. for the last worked on section) instead of loading its own.

To load the image alignment the user needs to click the "load image alignment" button. This is fine, but I think if the user's saved an alignment already they (I) would expect it would load next time the image is visited.

Thoughts / prayers?

[olivierdelree]

I'll probably make this the default for now and if I have time (I might not), I might make this a setting that can be toggled.