Big facelift

So, we had a pretty big update. Here's all the new stuff:

• The game now uses a fixed 16:9 resolution instead of changing the window size when you swapped modes.
• The cell sizes have been increased so you no longer need to squint
• Adjacent mine numbers are now colored (like the original)
• Fixed some nasty bugs
• Backgrounds now use a 16:9 resolution and have a tinted overlay on top to not clash with the board
• Some of the graphics have been altered; mines now have a cute little skull on them, and flags now actually have flags
• HUD is a little prettier now
• Clicking on a revealed cell will highlight any surrounding cells touching it. This should make it easier to tell where potential mines are

There's probably more stuff I forgot, but that's all I have to report for now. Enjoy!