IE<9 does some truly messed-up things when it sees these.

Another great JS feature banished for the foreseeable future by
the bunglers in Redmont, sigh.

Closes #1183

The window.onresize handlers registered for each editor would prevent
them from ever getting collected.

when checking whether the wrapper element is still part of the DOM, check all the way up to the document body

Issue #1178

These fire when the marker is removed/resurrected by editing and undo
operations.

Closes #1093

Closes #1176

Issue #1164

Operating on line widgets from within an operation would cause
crashes.

Add test.

When the matching symbol of a closing bracket is on a different
line, it will match to the incorrect opening bracket. For example,
go to http://codemirror.net/demo/vim.html and place the cursor on
the closing brace at line 11 and press '%'.  It will incorrectly
match the opening brace on line 4 instead of the brace on line 8.
This patch fixes that by starting the line search at the *end* of
the line when searching backwards.

Stop passing 'true' as a changeset to updateDisplay, simplify a bunch
of things.

`makeChangeSingleDocInEditor` was throwing exceptions because
of the typo.

The mark would disappear into thin air if it was on a line
affected by the undo (or redo). Now it is properly preserved.

Add docs for first-class document features, split API section
into subsections to make it easier to read.

 - Move a lot of methods from the CodeMirror to the Doc prototype
 - Allow getting, attaching, and copying of Doc objects
 - Add linkedDoc to create documents that stay in sync
 - Allow such linked docs to be sub-view on their parent
 - Rewrite history handling
 - Remove the concept of a view

Documentation still failing.

Issue #1166

Append image to wrapper. No more appending to document.
Works with multiple editors. Tested: 3 editors beneath each other on 1 page.