Client Files: Set flag when files enqueued and don't process files unless in current context (header/footer)
Client files: Do not set hooks when no files registered
Merge branch 'opt-file-enqueue' into develop
Viewer: Optimize theme validation
Viewer: Remove redundant code in `reset()` method (use existing API method)

Closes #110
Merge branch 'iss-110' into develop
Base: Stop script enqueue hook from passing arguments to callback
Base: Validate arguments in `enqueue_client_files()`
Merge branch 'fix-file-loading' into develop
Controller: Optimize hook initialization (don't set public hooks for admin requests)
Controller: Set hooks *after* request has been fully parsed

* Resolves #111
Merge branch 'fix-is_enabled-init' into develop