Fix from recent commit that broke required contexts in arrays, which broke panel views as well as mini panels

Fix for contexts so that arguments that fail to locate a context don't provide some false unusable context when they should be filtered out

#205527 by drayen, Soren Jones and yched: Fix warnings about empty contexts. Note to fully fix this, previous panels that demonstrate this warning will need to be resaved. Then the warning will go away.

#205611: (By Wim Leers): Code style cleanup for panels styles, plus API standardization (note: This means some minor API changes).

#177766: Use dedicated table for caching instead of actual cache to reduce volatility of stored panels data

Fixed re-bind so that if you edit a context-page modal twice the page doesn't just reload, causing you to lose all your changes

#201237: by Wim Leers -- load panels.module on mini panels uninstall so we can delete panels displays.