Constantly sync scroll left/top value from editor to edit session

Previously these values were only saved on the edit session when
is became inactive causing the scroll position to not always
persist between refreshes.

Closes #474

src/app/editor.coffee

@@ -656,7 +656,7 @@ class Editor extends View
       @scrollTop(@verticalScrollbar.scrollTop(), adjustVerticalScrollbar: false)
 
     @scrollView.on 'scroll', =>
-      if @scrollView.scrollLeft() == 0
+      if @scrollLeft() == 0
         @gutter.removeClass('drop-shadow')
       else
         @gutter.addClass('drop-shadow')
@@ -766,6 +766,7 @@ class Editor extends View
     @gutter.lineNumbers.css('top', -scrollTop)
     if options?.adjustVerticalScrollbar ? true
       @verticalScrollbar.scrollTop(scrollTop)
+    @activeEditSession.setScrollTop(@scrollTop())
 
   scrollBottom: (scrollBottom) ->
     if scrollBottom?
@@ -773,6 +774,20 @@ class Editor extends View
     else
       @scrollTop() + @scrollView.height()
 
+  scrollLeft: (scrollLeft) ->
+    if scrollLeft?
+      @scrollView.scrollLeft(scrollLeft)
+      @activeEditSession.setScrollLeft(@scrollLeft())
+    else
+      @scrollView.scrollLeft()
+
+  scrollRight: (scrollRight) ->
+    if scrollRight?
+      @scrollView.scrollRight(scrollRight)
+      @activeEditSession.setScrollLeft(@scrollLeft())
+    else
+      @scrollView.scrollRight()
+
   ### Public ###
 
   # Retrieves the {EditSession}'s buffer.
@@ -836,11 +851,11 @@ class Editor extends View
 
   setScrollPositionFromActiveEditSession: ->
     @scrollTop(@activeEditSession.scrollTop ? 0)
-    @scrollView.scrollLeft(@activeEditSession.scrollLeft ? 0)
+    @scrollLeft(@activeEditSession.scrollLeft ? 0)
 
   saveScrollPositionForActiveEditSession: ->
     @activeEditSession.setScrollTop(@scrollTop())
-    @activeEditSession.setScrollLeft(@scrollView.scrollLeft())
+    @activeEditSession.setScrollLeft(@scrollLeft())
 
   # {Delegates to: EditSession.setSoftTabs}
   toggleSoftTabs: ->
@@ -866,7 +881,7 @@ class Editor extends View
     @setSoftWrapColumn(softWrapColumn) if @attached
     if @activeEditSession.getSoftWrap()
       @addClass 'soft-wrap'
-      @scrollView.scrollLeft(0)
+      @scrollLeft(0)
       @_setSoftWrapColumn = => @setSoftWrapColumn()
       $(window).on "resize.editor-#{@id}", @_setSoftWrapColumn
     else
@@ -1036,10 +1051,11 @@ class Editor extends View
     desiredRight = pixelPosition.left + @charWidth + margin
     desiredLeft = pixelPosition.left - margin
 
-    if desiredRight > @scrollView.scrollRight()
-      @scrollView.scrollRight(desiredRight)
-    else if desiredLeft < @scrollView.scrollLeft()
-      @scrollView.scrollLeft(desiredLeft)
+    if desiredRight > @scrollRight()
+      @scrollRight(desiredRight)
+    else if desiredLeft < @scrollLeft()
+      @scrollLeft(desiredLeft)
+    @saveScrollPositionForActiveEditSession()
 
   calculateDimensions: ->
     fragment = $('<div class="line" style="position: absolute; visibility: hidden;"><span>x</span></div>')
@@ -1419,7 +1435,7 @@ class Editor extends View
     range = document.createRange()
     range.setEnd(textNode, offset)
     range.collapse()
-    leftPixels = range.getClientRects()[0].left - @scrollView.offset().left + @scrollView.scrollLeft()
+    leftPixels = range.getClientRects()[0].left - @scrollView.offset().left + @scrollLeft()
     range.detach()
     leftPixels