Proofread and updates for consistency of Swedish translation.
Fix crash from freeing backgroundsurface twice in MapRenderer

`backgroundsurface` is already freed in MapRenderer::clearLayers(), which
is called in MapRenderer's deconstructor.
Update of xgettext.py to support extraction of strings, fixes
issue with extraction of string with , and " as it breaks in
specialcase handling of extraction logic.

Script is tested on flare-game alpha_demo which was a great
testcase which produced a broken pot file and failed msgmerge.
Merge pull request #334 from hean01/master

Update of xgettext.py to support extraction of strings,
Merge pull request #332 from dorkster/bugfixes

Fix crash from freeing backgroundsurface twice in MapRenderer
Merge pull request #331 from hean01/translation

Proofread and updates for consistency of Swedish translation.
Updated engine.pot.
Updated swedish translate from updated pot file.
Merge pull request #335 from hean01/master

Updated engine.pot file and corresponding swedish translation.
Continuous integration: .travis.yml points to the updated irc channel.
Merge pull request #337 from stefanbeller/master

Change IRC channel in travis file.
Setup size of backgroundsurface depending on rerender distance.

When animated_tiles is switched off, the background will be rendered
into a static image and only renewed, when the player has moved a certain
distance specified in 'movedistance_to_rerender'.
Use this variable as well for the dimensions of the background surface.

Fixes #333
Merge pull request #338 from stefanbeller/master

Fixes #333
Merge remote-tracking branch 'upstream/master'