[Docs] Add spellchecking with pyenchant

- Use sphinxcontrib.spelling with custom wordlist.
- Skip the checking of the modules documents as they raise
false-positives.
- Add a setup.py spellcheck_docs command.
- Fix spelling and other issues.
- Add a doc favicon.

CHANGELOG.md

@@ -31,13 +31,13 @@
 
 ### Core
 
-- Fix Python 2 compatiblity issue with SimpleNamespace.
+- Fix Python 2 compatibility issue with SimpleNamespace.
 
 ## 2.0.1 (2019-06-07)
 
 ### Packaging
 
-- Fix setup.py build error without git installed.
+- Fix `setup.py` build error without git installed.
 
 ## 2.0.0 (2019-06-06)
 
@@ -55,16 +55,16 @@
   there to allow acting upon them.
 - Updated SSL/TLS Protocol parameters for better security.
 - Make the distinction between adding to the session new unmanaged torrents
-  and torrents loaded from state. This will break backwards compatability.
+  and torrents loaded from state. This will break backwards compatibility.
 - Pass a copy of an event instead of passing the event arguments to the
-  event handlers. This will break backwards compatability.
+  event handlers. This will break backwards compatibility.
 - Allow changing ownership of torrents.
 - File modifications on the auth file are now detected and when they happen,
   the file is reloaded. Upon finding an old auth file with an old format, an
   upgrade to the new format is made, file saved, and reloaded.
 - Authentication no longer requires a username/password. If one or both of
   these is missing, an authentication error will be sent to the client
-  which sould then ask the username/password to the user.
+  which should then ask the username/password to the user.
 - Implemented sequential downloads.
 - Provide information about a torrent's pieces states
 - Add Option To Specify Outgoing Connection Interface.
@@ -77,13 +77,13 @@
 - Host entries in the Connection Manager UI are now editable.
 - Implemented sequential downloads UI handling.
 - Add optional pieces bar instead of a regular progress bar in torrent status tab.
-- Make torrent opening compatible with all unicode paths.
+- Make torrent opening compatible with all Unicode paths.
 - Fix magnet association button on Windows.
 - Add keyboard shortcuts for changing queue position:
-  - Up: Ctrl+Alt+Up
-  - Down: Ctrl+Alt+Down
-  - Top: Ctrl+Alt+Shift+Up
-  - Bottom: Ctrl+Alt+Shift+Down
+  - Up: `Ctrl+Alt+Up`
+  - Down: `Ctrl+Alt+Down`
+  - Top: `Ctrl+Alt+Shift+Up`
+  - Bottom: `Ctrl+Alt+Shift+Down`
 
 ### Web UI
 
@@ -93,7 +93,7 @@
 ### Blocklist Plugin
 
 - Implemented whitelist support to both core and GTK UI.
-- Implemented ip filter cleaning before each update. Restarting the deluge
+- Implemented IP filter cleaning before each update. Restarting the deluge
   daemon is no longer needed.
 - If "check_after_days" is 0(zero), the timer is not started anymore. It
   would keep updating one call after the other. If the value changed, the