no longer allows backtracking, no longer allows line crossing

there is a bug somewhere between the line crossing and backtracking
where if it stops backtracking it will still allow line crossing
Kyle and my code merged
Merge branch 'gui-merging' of https://github.com/floft/sprouts into gui-merging
Test

Work on preventing line crossing on final click
Node Connection to not cross

Horizontally connecting to node is having problems.
insert node function is no longer commented out
Menu added
load images once, don't make them transparent, exit game
The images were being set with transparency by default in the Image
class, which now is optional. Now they look a lot better. The game now
exits when clicking exit, breaking out of the first loop and skipping
the game loop. And, the images are now loaded once before showing the
menu instead of as the mouse is moved.
reduce CPU usage by waiting a few milliseconds
set window title before opening the menu
made it unnecessary to move mouse after clicking on a button to move on to the next screen
the menu is now in a separate function. Escape now returns to the menu.

I also prepared the program to allow the user to select their own name,
whether the game is PvP or PvAI, and the number of nodes
fixed a small mistake
Merge branch 'gui-merging'

Conflicts:
	gamegui.cpp
Got rid of hack in 51b1e76dbea09e2cba73a2f43ba48583c0cd6e2f
Luke realized that isInArea() was counting it as the wrong odd/even not
because it was not detecting a node on the start/endpoints of a line but
because it was detecting it as intersecting both. Keeping one of the "or
equal to" checks and getting rid of the other made it work. Now it's
less than or equal to max Y and greater than min Y.
moved menu to a Menu class
This allows the images to be loaded once instead of multiple times.
added back in the Esc event
I accidentally deleted it.
Merge branch 'gui-menu'

Conflicts:
	gamegui.cpp
	main.cpp

I think it looks pretty cool. As Michael continues to add to it, I or he
can remerge it. If it's annoying having to click start all the time
while debugging, I can revert this merge and merge it later.
initial improvement of README
added parentheses g++ was warning about