Issue #1168272: Retool block.inc to support block_list_alter and thus things like i18n block translation.

Forward port the fixes from 6.x which where mostly done but cleanup extra
lines added to the top of php files and some slight mistakes.

Issue #1235218: Restore "node" keyword to node add/edit forms so they can act like node contexts again.

Issue #1223532: Multiple terms required context not available to Views and Multiple term required context not usable as a single term context because of entity change over.

Issue #1195686: Typo in entity name causing notices and broken context on term from node relationship.

Issue #1193886: node edit form often only has "Form goes here" due to bad recursion prevention code.

Issue #1206230: Really allow exposed form in block. Requires matching commit from Views to work, but should no longer break anything.

This reverts commit 33d72942.