When any specified pair is empty, backspacing will also
delete the closing bracket.

Just a small nit. Without the list check, `getStateAfter`
looks like it will always be true.

Closes #1337

Closes #1336

It had been depending on the list token being highlighted
with the class 'string', which it no longer is in the markdown
mode.

Updated to check the `list` property of the line's state.

These changes are experimental, not documented yet, and might not end up
in the stable API.

Issue #1321

The state.tokenize property could return an array, but the token
method didn't count on that.

Closes #1326

Allows correct hinting even when the tag is multi-line by achieving a
dot matches all effect by using [\s\S] instead.

Issue #1317

With the eclipse theme, if you move your cursor on a bracket and have the matching bracket option enabled, spans with borders are inserted. They push the rest of the line to the right by the amount of the border width, which looks very crappy. Using outline instead of border fixes this

Ran into this when trying to include CodeMirror from Browserify - the
path of `codemirror.js` doesn't point to the necessary
`lib/codemirror.js` file.

Closes #1310

Issues #988, #742, #612, etc. show that CodeMirror users tend to:

1. Not find how to make the Tab key insert spaces instead of a tab,
2. Miss how to use extraKeys to easily solve the issue.

Adding an example helps them find a solution immediately.

This was causing "1^2" to tokenize as: (number, "1"), (variable, "^2). By
tokenizing these bitwise operators as operators CodeMirror can correctly
syntax highlight the 2 as a number. Likewise the number in "~0".