add split, vsplit, sp, and vsp commands

lib/ex.coffee

@@ -4,6 +4,31 @@ class Ex
       atom.workspace.getActiveEditor().save()
     else
       atom.workspace.getActivePane().saveActiveItemAs()
+
   w: => @write()
 
+  split: (filePaths) ->
+    pane = atom.workspace.getActivePane()
+    if filePaths? and filePaths.length > 0
+      newPane = pane.splitUp()
+      for file in filePaths
+        do ->
+          atom.workspace.openURIInPane file, newPane
+    else
+      pane.splitUp(copyActiveItem: true)
+
+  sp: (filePaths) => @split(filePaths)
+
+  vsplit: (filePaths) ->
+    pane = atom.workspace.getActivePane()
+    if filePaths? and filePaths.length > 0
+      newPane = pane.splitLeft()
+      for file in filePaths
+        do ->
+          atom.workspace.openURIInPane file, newPane
+    else
+      pane.splitLeft(copyActiveItem: true)
+
+  vsp: (filePaths) => @vsplit(filePaths)
+
 module.exports = Ex