Rename subsurface.svg to subsurface-icon.svg

In preparation for a subsurface-icon.h, this should avoid confusion
about whether "subsurface.h" is a core header file.

Signed-off-by: Henrik Brautaset Aronsen <subsurface@henrik.synth.no>
Move about icon to include file

Getting the about icon to display in various scenarios on MacOSX
was a pain.  Moving the icon to an include file solved the problem.

This commit also fixes the problem Dirk was having when converting
satellite.svg to a png in commit cf3c0266c2.  I couldn't
quite get ImageMagick to preserve transparency and color when
converting subsurface-icon.svg, though, so I used Gimp instead.

Signed-off-by: Henrik Brautaset Aronsen <subsurface@henrik.synth.no>
Merge branch 'subsurface-icon' of github.com:henrik242/subsurface
Updated Russian translation in preparation for v3.0

Some strings are not translated yet due to minor bugs.
Needs to be discussed on the mailing list.

Signed-off-by: Sergey Starosek <sergey.starosek@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>