Remove the icons that are not mirrored to regular locations. And moved the icons that need mirroring to mirrored locations. Replaced "octicon-chevron-right" with new set of mirrored icons from fontello

swipebox has not built in support for RTL, and without this fix the images will display outside of the window range since it does the calculation for the window location assuming every thing is aligned left, and that is hard-coded in its javascript and cannot be overridden with css.

The easiest fix which is proposed here is to override the global RTL just for swipebox, and make it display in LTR to match its calculations. The problem however, is that the Next and Prev buttons are still in LTR direction which is the opposite of what users of RTL expect.

The other solution is to either replace swipebox with something that is RTL aware, or modify swipebox code to add RTL support.

- Some bug fixes 
- Additional support

A lot of fixes for RTL

Updated the name of the flex-nav element for RTL from `hidden` to the correct name `animated-hidden`

These changes alters the theme of the text-area and the upload button to look correct with RTL interface.

Adding initial en.i18n translations.

This change also alters how edits are displayed both for sequential
and non-sequential messages.

See #1357

This comes in the form of the user's avatar, along with a hover
title that shows username and edit time. As a side note, this
requires us to start saving 'editBy' id as part of message updates.

This has been tested with all 4 of the current avatar methods.

fixes #824

Note that this also makes a minor tweak to scope of "if description"
check in admin.html, that is more correct.

This change also swaps out the settings group display from <h3>
to <p> for a better look and feel.

Firefox interprets user-select: all; to mean that any clicks should result in
the entire element's container being selected, regardless of the user's gesture.
This results in the inability to select only a subset of characters in a chat
message.

Fixes #1242