Add hedgehog effect heArtillery, allows to set per-hedgehog artillery mode
Allowed effect values:
0 = not active
1 = permanently active
2 = termporarily active (sniper rifle)
07f3bf8d98a3
Hedgewars.png had a resolution more than twice as high as required; also fixed some (mostly obsolete) code that also contained a typo that would cause a warning/note in clang
