Stop minigun sound when gtMinigun is destroyed

QT for some reason messes with XCompose causing broken input (Qt 5 only - Qt 4 did not break anything). In Qt 5.2 and 5.3 this was causing an invalid conversion in chat messages containing these resulting in the bad bytes being stripped. In Qt 5.9 it is still broken, but you at least get a string with something in it. This checks for non-zero converted strings for room creation and chat lines.

Fix bullet trails overlapping when the pass through wrap or bounce world edge

Use QDir::Files to read ammo schemes

Don't let hedgehogs moan if they take 0 Sudden Death damage

Fix minigun bullets hitting shooter when it hits hog on other side of world wrap

Update changelog