tests: improved Latte tests, removed codefix()
Latte: optimizePhp() moved to Latte\Helpers
Latte: optimizePhp() supports <?xml declarations
Latte: new Engine API
tests: Latte tests updated for new API
Latte: removed Compiler::$defaultContentType (BC break)
Latte: added Parser::setContentType()
Latte: loaded Nette\Latte\Runtime\Filters is registered automatically