main: Fix some icons not being symbolic anymore

Hatchet job when we started using GTK+'s automatic RTL icon support.

Spotted by jimmac and Lapo.
data: Make all aspect ratios use the ratio sign

A regression caused by commit
8ff9c0d1dd058d60696eed6a778e2750ac02fac1

https://bugzilla.gnome.org/show_bug.cgi?id=731671