- Adding a postload filter for `status_header` so that Quick Cache can p...

List of changes in this PR. This includes changes across both the lite and pro versions. I'm submitting a separate PR for each version of the software (i.e. the lite and pro versions).

- Adding a postload filter for `status_header` so that Quick Cache can properly detect calls to the WP core function `status_header()`.
- Resolving <https://github.com/WebSharks/Quick-Cache/issues/113>
- Resolving <https://github.com/WebSharks/Quick-Cache/issues/114>
- Improving docBlocks in Auto-Cache Engine class.
- Adding docBlocks to the new API class.
- Updating API for IDE conformity.