Lua API: Remove BorderColor variable from onGameInit
Seems to be broken, returns negative value, is not used in any script, obscure feature anyway.
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.