Never use more than 3 divs to render a selection

This should hopefully improve performance for large selections.

src/atom/editor.coffee

@@ -54,7 +54,7 @@ class Editor extends Template
       @on 'newline', =>  @insertNewline()
       @on 'backspace', => @backspace()
       @on 'delete', => @delete()
-      @on 'copy', => @copyText()
+      @on 'copy', => @copySelection()
 
 
     buildCursorAndSelection: ->
@@ -192,5 +192,5 @@ class Editor extends Template
     insertNewline: -> @selection.insertNewline()
     backspace: -> @selection.backspace()
     delete: -> @selection.delete()
-    copySelection: -> @selection().copy()
+    copySelection: -> @selection.copy()
 

src/atom/selection.coffee

@@ -34,26 +34,22 @@ class Selection extends Template
 
       range = @getRange()
       return if range.isEmpty()
-      for row in [range.start.row..range.end.row]
-        start =
-          if row == range.start.row
-            range.start
-          else
-            { row: row, column: 0 }
 
-        end =
-          if row == range.end.row
-            range.end
-          else
-            null
+      rowSpan = range.end.row - range.start.row
 
-        @appendRegion(start, end)
+      if rowSpan == 0
+        @appendRegion(1, range.start, range.end)
+      else
+        @appendRegion(1, range.start, null)
+        if rowSpan > 1
+          @appendRegion(rowSpan - 1, { row: range.start.row + 1, column: 0}, null)
+        @appendRegion(1, { row: range.end.row, column: 0 }, range.end)
 
-    appendRegion: (start, end) ->
+    appendRegion: (rows, start, end) ->
       { lineHeight, charWidth } = @editor
       top = start.row * lineHeight
       left = start.column * charWidth
-      height = lineHeight
+      height = lineHeight * rows
       width = if end
         end.column * charWidth - left
       else