Optimize all SVGs

Passed with svgo 0.4.2 <https://github.com/svg/svgo>, then prepended
'<?xml version="1.0" encoding="UTF-8"?>' prolog to each file since
svgo sees it fit to remove it and that breaks file type detection.
svgo truncated all numerical values to a maximum of 3 decimal places
of precision.

world_map.svg: Removed very tiny separated path segments (by
insetting and then outsetting the path). Scaled down to the size at
which the image is used. This makes the image smaller than 32 KiB so
it will now be inlined be resource loader instead of beign requested
separately.

Image            orig     new
clear            1268     298
close            1370     369
icon-language    2560    1816
search           1025     480
world_map       71624   19488