Util: Add more control over internal hooks

* Secondary hook prefix can be customized or omitted entirely
Update internal hooks (options)
Update internal hooks (admin)
Update internal hooks (fields)
Merge branch 'opt-hooks' into develop
Controller: Stop output if no links have been activated
Util: Remove trailing whitespace
Controller: Aggregate script output into single `script` element
Themes: Aggregate script output into global `script` element
Content Handlers: Aggregate script output into global `script` element
Template Tags: Aggregate script output into global `script` element
Cleanup comments
Merge branch 'opt-client-output' into develop
Update inline documentation
Content: Validate URIs

* Add: Regex pattern matching
* Add: Default patterns
* Add: Validation cache (for faster validation of repeated URIs)
* Closes #11
Merge branch 'filter-links' into develop
Content: Cache links without valid handlers

* Speeds up processing for repeated links