remove cleaver gradient

merge trunk in 0.9.18

dev version bump, for 'stable' commits please use 0.9.18 branch

disable this block since it doesn't fit star's new graphic. doesn't show up often anyway, since unc0rr changed gst clearing

use VideoItem::prefix instead of VideoItem::name as suggested by Stepan777

tweaked hedgehog sprite (gstLoser and such) this version tries to clean up a bit of the pixelation from having not been edited in inkscape

Change messages a bit

Mutant script

Fix training script positions altered by variable land dimension change. issue #453

Fix 440, used 'grave' rather than '`' in default binds

darken and contrast the gray images to distinguish more easily from pink

Arbitrarily tweaked to not firepunch loose, and to increase chance of bazooka doing it to about 20%

Improve TestSniperRifle a bit

Allow cleavers to be knocked loose by explosions. Probabilities might need tweaking.