FMod - Improved Time Machine

Today I made some tweaks to the Time Machine feature. The normal TileUndo class now records which tool was active when it was instantiated and adds a "using tool" phrase to the end of its description. The word "tiles" is now singularized when there was only one tile modified. Clear History now requires confirmation before doing its work, which - naturally - cannot be undone. Finally, I made sure the Time Machine window can't be resized in a way that hides some of the buttons.

The improved Time Machine

Visual Studio 2015 bug: the dividing lines between methods and other important stuff don't extend to the right when the horizontal scroll bar is used in the code window.