Hats webpage: Many improvements and fixes (2nd try) * Fix static hats not being animated properly * Make widges more user-friendly * Add local mode to hats webpage to make testing easier (IS_LOCAL variable) * Cleanup code * Update themes list * Update list of local hats

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.