git-gui: Improve the application icon on Windows.
git-gui: Improve the application icon on Windows.

Previusly, there was only a 16x16 image, which looked very distorted.
Here we add a 32x32 version, and also make the image sharper.

Signed-off-by: Johannes Sixt <5cc107486946fdcf16e86d7c808fa50f4312125f@telecom.at>
Signed-off-by: Shawn O. Pearce <f01032651c12a22b2103346ba96b3b6b231f9d3c@spearce.org>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git