Start adding marker methods to DisplayBuffer

Whereas marker methods on buffer take for granted that everything is
in buffer coordinates, methods on the DisplayBuffer offer both
screen and buffer coordinate versions of the marker API.

src/app/display-buffer.coffee

@@ -296,12 +296,51 @@ class DisplayBuffer
   markBufferRange: (bufferRange) ->
     @buffer.markRange(bufferRange)
 
+  markScreenPosition: (screenPosition) ->
+    @markBufferPosition(@bufferPositionForScreenPosition(screenPosition))
+
+  markBufferPosition: (bufferPosition) ->
+    @buffer.markPosition(bufferPosition)
+
   getMarkerScreenRange: (id) ->
     @screenRangeForBufferRange(@getMarkerBufferRange(id))
 
   getMarkerBufferRange: (id) ->
     @buffer.getMarkerRange(id)
 
+  getMarkerScreenPosition: (id) ->
+    @getMarkerHeadScreenPosition(id)
+
+  getMarkerBufferPosition: (id) ->
+    @getMarkerHeadBufferPosition(id)
+
+  getMarkerHeadScreenPosition: (id) ->
+    @screenPositionForBufferPosition(@getMarkerHeadBufferPosition(id))
+
+  setMarkerHeadScreenPosition: (id, screenPosition, options) ->
+    @setMarkerHeadBufferPosition(id, @bufferPositionForScreenPosition(screenPosition, options))
+
+  getMarkerHeadBufferPosition: (id) ->
+    @buffer.getMarkerHeadPosition(id)
+
+  setMarkerHeadBufferPosition: (id, bufferPosition) ->
+    @buffer.setMarkerHeadPosition(id, bufferPosition)
+
+  getMarkerTailScreenPosition: (id) ->
+    @screenPositionForBufferPosition(@getMarkerTailBufferPosition(id))
+
+  setMarkerTailScreenPosition: (id, screenPosition, options) ->
+    @setMarkerTailBufferPosition(id, @bufferPositionForScreenPosition(screenPosition, options))
+
+  getMarkerTailBufferPosition: (id) ->
+    @buffer.getMarkerTailPosition(id)
+
+  setMarkerTailBufferPosition: (id, bufferPosition) ->
+    @buffer.setMarkerTailPosition(id, bufferPosition)
+
+  isMarkerReversed: (id) ->
+    @buffer.isMarkerReversed(id)
+
   destroy: ->
     @tokenizedBuffer.destroy()