Ticket 4665 - Emoji Picker (#5157)

*  #4665  Added EmojiPicker

Work primarily by @broernr-de and @harrison on pre-release.mattermost.com

* Final fixes to handle custom emojis from internal review and single merge error

* ESLint fixes

* CSS changes and other code to support emoji picker in reply window

* Fix for file upload and emoji picker icon positions on post and comment.

RHS emoji picker appearing see-through at this time.

* Fix for two ESLint issues.

* covered most of feedback:
RHS emoji picker looks correct color-wise
RHS emoji picker dynamically positions against height of thread size (post + reply messages)
escape closes emoji window
search box focused on open

ESLint fixes against other files
oversized emoji preview fixes

* Adding in 'outside click' eventing to dismiss the emoji window

* Changing some formatting to fix mismatch between my local eslant rules and jenkins.

* adding alternative import method due to downstream testing errors

* yet another attempt to retain functionality and pass tests - skipping import of browser store

* fix for feedback items 5 and 7:
* move search to float on top with stylistic changes
* whitespace in the header (+1 squashed commit)
Squashed commits:
[6a26d32] changes that address items
1, 2, 6, 8, and 9 of latest feedback

* Fix for attachment preview location on mobile

* Fix for latest rounds of feedback

* fixing eslint issue

* making emojipicker sprite based, fixing alignments

* Fix for emoji quality, fixing some behavior (hover background and cursor settings)
undoing config changes

* Preview feature for emojis

* Adjustments to config file, and changing layout/design of attachment and emoji icon.

* manual revert from master branch for config.json

* reverting paperclip and fixing alignments.  Additionally fixing inadvertent display of picker on mobile.

* CSS changes to try to fix the hover behavior - currently working for emoji picker (when enabled), but hover for attachment isn't working

* Made suggested changes by jwilander except for jQuery removal

* Adding hover for both icons

* removal of some usages of jQuery

* Fix for two layout issues on IE11/Edge

* UI improvements for emoji picker

* Fix for many minor display issues

* fix for additional appearance items

* fix to two minor UI items

* A little extra padding for IE11

* fix for IE11 scroll issue, and removing align attribute on img tag which was throwing js error

* fixes some display issues on firefox

* fix for uneven sides of emojis

* fix for eslint issues that I didn't introduce

* fix for missing bottom edge of RHS emojipicker.  also fixing text overlapping icons on text area (including RHS)

* Update "emoji selector" to "emoji picker"

* changes for code review
- removal of ..getDOMNode
- use sprite imagery for emoji preview
- remove lastBlurAt from state as it wasn't used

* fixes for:
- fake custom emoji preview in picker
- RHS scrollbar on preview

* fix for minor alignment of preview emoji

webapp/i18n/en.json

@@ -1287,6 +1287,18 @@
   "emoji_list.name": "Name",
   "emoji_list.search": "Search Custom Emoji",
   "emoji_list.somebody": "Somebody on another team",
+  "emoji_picker.activity": "Activity",
+  "emoji_picker.custom": "Custom",
+  "emoji_picker.emojiPicker": "Emoji Picker",
+  "emoji_picker.flags": "Flags",
+  "emoji_picker.food": "Food",
+  "emoji_picker.nature": "Nature",
+  "emoji_picker.objects": "Objects",
+  "emoji_picker.people": "People",
+  "emoji_picker.recent": "Recently Used",
+  "emoji_picker.search": "Search",
+  "emoji_picker.symbols": "Symbols",
+  "emoji_picker.travel": "Travel",
   "error.not_found.link_message": "Back to Mattermost",
   "error.not_found.message": "The page you were trying to reach does not exist",
   "error.not_found.title": "Page not found",
@@ -1989,6 +2001,7 @@
   "user.settings.advance.slashCmd_autocmp": "Enable external application to offer slash command autocomplete",
   "user.settings.advance.title": "Advanced Settings",
   "user.settings.advance.webrtc_preview": "Enable the ability to make and receive one-on-one WebRTC calls",
+  "user.settings.advance.emojipicker": "Enable emoji picker in message input box",
   "user.settings.custom_theme.awayIndicator": "Away Indicator",
   "user.settings.custom_theme.buttonBg": "Button BG",
   "user.settings.custom_theme.buttonColor": "Button Text",