Removed: Unused code and fixed naming

[alexander-zierhut]

Every compiled view had <?php ##PATH ## ?> appended to it. The path interpolation that once filled the marker was dropped with the ViewFinder refactor, so all it does now is write an empty comment into each cached file, and nothing reads it back.

The rest is naming and dead declarations. viewExists() carried a bool $isComponent parameter it never read, the check is done with instanceof. ERROR_INVALID_CONFIG is referenced nowhere, the constructor throws the more specific path messages instead. The auth message pointed at Config::setAuth, which does not exist, the method is setAuthCallback(). The local $complied in compile() is now $compiled, matching $compiledPath beside it and the saveCache() parameter it feeds.

Dropping the viewExists() parameter changes a public signature. Nothing in the library passes it, but it is the one change here that can reach a consumer.