Autoscroll to the last cursor in model when inserting text

Fixes #2787

spec/editor-spec.coffee

@@ -1483,6 +1483,17 @@ describe "Editor", ->
             expect(cursor1.getBufferPosition()).toEqual [1, 5]
             expect(cursor2.getBufferPosition()).toEqual [2, 7]
 
+          it "autoscrolls to the last cursor", ->
+            editor.manageScrollPosition = true
+            editor.setCursorScreenPosition([1, 2])
+            editor.addCursorAtScreenPosition([10, 4])
+            editor.setLineHeightInPixels(10)
+            editor.setHeight(50)
+
+            expect(editor.getScrollTop()).toBe 0
+            editor.insertText('a')
+            expect(editor.getScrollTop()).toBe 80
+
       describe "when there are multiple non-empty selections", ->
         describe "when the selections are on the same line", ->
           it "replaces each selection range with the inserted characters", ->

src/selection.coffee

@@ -315,6 +315,7 @@ class Selection extends Model
     wasReversed = @isReversed()
     @clear()
     @cursor.needsAutoscroll = @cursor.isLastCursor()
+    @cursor.autoscroll() if @editor.manageScrollPosition and @cursor.isLastCursor()
 
     if options.indentBasis? and not options.autoIndent
       text = @normalizeIndents(text, options.indentBasis)