Files.php The only class containing other scripting and not in classes/

Used, at least for now, entirely for appCache since Firefox doesn't like my
headers or something.

Sets correct cache-control, mime-type, etc for files.
Just some indentation fixes.
Use files.php (magic_cache class) for sending manifest.appcache

Updated manifest.appcache to include all current resources.
Use <?=URL?> when setting manifest

If not at root of site, it will be set incorrectly I guess and does not
seem to respect <base>
Turns out it doesn't work to have appCache on every page.

The whole thing is causing lots of problems anyways.
Disabled appCache for now
Fixed appcache logic