Made improvements to the context menu.

- Added option to disable even/odd coloring

Personally I can't stand the colored context menu. It took my eyes a moment to figure out what was even going on when I first opened it. I added an option to removed the even/odd coloring, while keeping the bottom-most option colored:
![alternate context menu](https://dl.dropboxusercontent.com/u/11093974/Junk/contextmenu.png)

- Fixed context menu not updating when config was reloaded

When reloading the config file, the context menu settings wouldn't update. At first I was very confused what the "ContextMenuShowMargins" options did, because upon refreshing I noticed no difference. Hopefully this should avoid confusion for anyone else!