ui: Much elm work, such wow

- ui: Fix favicon
- webui: Changes to support serving Elm UI
- Static files now served from `/` mount point.
- Old UI handlers moved to `/serve` mount point, some will still be
  needed by the Elm UI; safe HTML and attachments for example.
- Update dev-start.sh for new UI, with tip on how to build it.
- ui: Detect browser host:port for websocket URL,
- webui: Remove unused mailbox handlers, rename routes
- Many routes not needed by Elm UI.
- `/serve/mailbox/*` becomes `/serve/m/*`.
- webui: Impl custom JSON message API for web UI,
- ui: Refactor Mailbox view functions,
- ui: Add body tabs for safe HTML and plain text,
- webui: Format plain text for new UI,
- ui: List attachments with view & download links,

ui/src/Data/Session.elm

@@ -12,10 +12,12 @@ module Data.Session
 
 import Json.Decode as Decode exposing (..)
 import Json.Decode.Pipeline exposing (..)
+import Navigation exposing (Location)
 
 
 type alias Session =
-    { flash : String
+    { host : String
+    , flash : String
     , routing : Bool
     , persistent : Persistent
     }
@@ -35,9 +37,9 @@ type Msg
     | AddRecent String
 
 
-init : Persistent -> Session
-init persistent =
-    Session "" True persistent
+init : Location -> Persistent -> Session
+init location persistent =
+    Session location.host "" True persistent
 
 
 update : Msg -> Session -> Session