Cleanup (unneeded) icon aliasing (#264)

This cleanup mainly focuses in horizontal/vertical lines that have
aliasing (likely due to misaligned scaling from some source)

I am no artist (far from it), so I only touched up horizontal/vertical
aliasing issues. If someone wants (feels the need) to take on diagonal
lines, feel free to contribute! (Aliasing on diagonal lines make more
sense, so they might be fine)

Fixes #97

Author: shpaass

Yafc/Data/Icons/Add.png

@@ -29,6 +29,7 @@ Date:
         - You can now open projects from a Windows context-menu. If the project was not opened before, then Yafc uses
           the launch-settings from the most-recently opened project.
         - Move the Legacy Summary and Import from clipboard buttons to the main/hamburger menu.
+        - Clean up (unneeded) aliassing from icons.
     Bugfixes:
         - Several fixes to the legacy summary page, including a regression in 0.8.1.
         - Crafters with no enery_source no longer make Yafc refuse to solve the page.