+Save menu item with blank handler
+SaveFileDialog we'll use for saving images
Now asking for a file name and saving if accepted
-Unnecessary using directive
Tracks the Save enabledness properly
+Tools menu
+Pen menu item with shortcut
+Rectangle menu item
+Blank handlers for Pen and Rectangle
+Blank ToolType enum
Values for Pen and Rectangle
+ToolType property that dictates which tool we're using

Updates the Tool menu's item as to which is checked.
Only drawing lines on Pen tool
Tracks the rectangle you drag out with the Rectangle tool
Draws a rectangle when you let up after dragging