Upgrade to CodeMirror 5.13.2

See http://codemirror.net/doc/releases.html

9-02-2016: Version 5.12:
Vim bindings: Ctrl-Q is now an alias for Ctrl-V.
Vim bindings: The Vim API now exposes an unmap method to unmap bindings.
active-line addon: This addon can now style the active line's gutter.
FCL mode: Newly added.
SQL mode: Now has a Postgresql dialect.
Fix issue where trying to scroll to a horizontal position outside of the document's width could cause the gutter to be positioned incorrectly.
Use absolute, rather than fixed positioning in the context-menu intercept hack, to work around a problem when the editor is inside a transformed parent container.
Solve a problem where the horizontal scrollbar could hide text in Firefox.
Fix a bug that caused phantom scroll space under the text in some situations.
Sublime Text bindings: Bind delete-line to Shift-Ctrl-K on OS X.
Markdown mode: Fix issue where the mode would keep state related to fenced code blocks in an unsafe way, leading to occasional corrupted parses.
Markdown mode: Ignore backslashes in code fragments.
Markdown mode: Use whichever mode is registered as text/html to parse HTML.
Clike mode: Improve indentation of Scala => functions.
Python mode: Improve indentation of bracketed code.
HTMLMixed mode: Support multi-line opening tags for sub-languages (<script>, <style>, etc).
Spreadsheet mode: Fix bug where the mode did not advance the stream when finding a backslash.
XML mode: The mode now takes a matchClosing option to configure whether mismatched closing tags should be highlighted as errors.