Fix handling of electricChars in multi-line edits

Closes #2804
Make parentheses visible while under `matchingbracket` rule

Code: Brackets now become black when they are highlighted as "matching".
JSON: key names are now in "white" (json was a bit saturated with orange - keys and string values).
Cleanup: removed some unnecessary rules.
Default face color normalized to #ffffec (was #ffffe9).
[show-hint addon] Give active hint color more precedence

To make it easy for client code to color completions without clashing
with the selected styling.
Update shell.js
Added wordsOnly option. Updated documentation.
Add example of using markselection to style background to demo
Add links to addon docs in mark-selection demo
Support upper-case SCRIPT tags in htmlmixed mode
[xml mode] Mark <menuitem> as self-closing tag

Closes #2810
[rst mode] Remove assertion mechanism

Throwing exceptions is a really bad way to deal with unexpected
syntax in a highlighting mode.

Closes #2805
Update realworld.html

Added hawkee.com
Mark release 4.6
Bump version number post-4.6
[markdown mode] test case for #2813

after header immediately followed by a code block, GFM formatting is
broken (SHA, #issue, URLs).

overlay.codeBlock gets it wrong (false inside fenced block, true after).
Not yet sure why.
[markdown] Fix handling of forced blank lines (after headers)

Closes #2813
[dylan mode] Remove executable flag on mode demo page

Closes #2816
Move to new github repository (under codemirror organization)
Update travis icon link in README
Also update the actual link to Travis

Ugh.
[lint addon] Sanitize passing arguments to hint sources. Somewhat incompatible

This might break sites that depend on async linters getting an editor instance
as first arg, or sync linters getting the .options property of the options passed
as second argument. The args passed are now more or less consistent.