Let window size depend on the screenshot aspect ratio
Summary:
Now the window width size changes with the aspect ratio of the captured image.
Maximum width is 1000 pixels for this automatic resize.
Test Plan:
Reviewers: ngraham, Spectacle, rkflx
Reviewed By: ngraham, Spectacle, rkflx
Subscribers: rkflx, ngraham
Tags: Spectacle
Differential Revision: https://phabricator.kde.org/D10377