GitLab

* Cache protocol-specific pages
* Ignore all query args and hashes, not just that used to clear a page's cache

Fixes #2.

Probably needs a new name.

Since admin requests aren't routed through the cache frontend, the global variable isn't available. Use defines for these overrides instead.

Unfortunately does mean that settings are split, but alternatives weren't appealing:
* store settings into an option via the front-end proxy (front-end writes are bad)
* store in Redis (could lose the option, randomly revealing a UI)
* pass all wp-admin requests through the proxy with early bailing to avoid breakage seems overly complicated and fragile/prone to bugs.

Improve use of global space by declaring a local variable global, rather than always using the Superglobal.

It's easier to read, especially with the use of the `$_SERVER` superglobal.

Conslidates debug messages and prevents them from corrupting XML layouts.

Revert helper function for loading WP, introduced in 25ebf3a1. It causes the brokenness noted in that commit, somehow related to calling require_once inside a function.

Currently broken (causes an error with $wpdb).

Clarify purpose of `cache` flag by renaming to `cached` as it indicates that the current page was served from cache

Update companion plugin to use global settings introduced in aa697f90 and 0a647e33, simplifying administration, ensuring consistency in settings used, reducing UI clutter.

Move configuration into a global and update all references. Makes for clearer separation of user options versus plugin code.

Improve detection for logged-in users and correct order of operations to ensure logged-in users aren't shown cached pages.

Add support for non-standard port and database values, remove dangerous information from debugging output.