Enhancement: add compression quality override for lossy file formats

[Szeniel]

Hi!
I couldn't find a setting that would determinate with what % of quality this program exports jpgs.
If it would be possible it would be nice to have that in % scale 1-100.

[VoxelCubes]

Currently it uses the same quality as the original image was set to when it was exported. Though, if the input wasn't jpeg, that won't carry over and a default value is used. I should offer a quality override, I suppose. This would fit very nicely on a new export page for the profile that would also house the new file name suffixes overrides you suggested earlier. Good idea!

P.S. thanks for all the awesome ideas! I just wish I had time to work on them sooner, but soon enough, I assure you.