Make shadow sizes linear
Summary: Before, shadow size doubled with each new size until Very Large and the smaller shadows were more transparent than the larger shadows. Now shadow size increases linearly and smaller shadows start with more opacity so that they don't become nearly invisible. The new shadows should look better on cheap displays.
Test Plan:
Before
Small:
Medium:
Large:
Very Large:
After
Small:
Medium:
Large:
Very Large:
Reviewers: VDG, Breeze, ngraham, rooty
Reviewed By: VDG, Breeze, ngraham, rooty
Subscribers: filipf, ngraham, zzag, rooty, plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D19148