Make cake bounce off bounce edge, stop cake at wrap edge to prevent other bug
The "other bug" is that the cake just walks through terrain when it hits the wrap world edge. This behaviour is even worse.
Lua scripts for engine testing. These scripts are the same as other Lua scripts
in Hedgewars, but you ought to call `EndLuaTest(TEST_SUCCESSFUL)` or
`EndLuaTest(TEST_FAILED)` when the test is completed.