Fixed CPU usage when out of focus

Fixes the bug that CPU usage increase dramatically when the game is
frozen. The game is frozen when out of focus by default. So if I have an
empty game that takes like 1%, when I make it loose focus it goes to 17%
(probably at least 1 of my 8 cores on max). It looses focus also when
minimized, so minimizing a game with "Freeze the game when it looses
focus" option makes it jump to 17%.

This happens because the "freeze" thing happens in main loop and is
checked with:

>if (enigma::gameFroze) continue;

This basically means that it's running an empty loop as fast as
possible, thus using all the resources it can. It can be fixed by doing
adding a delay in the loop. I added 100000us, which means it will only
run the loop 10 times a second. We can increase/decrease the delay if
needed. But now the game uses 0% of CPU when frozen or minimized.
Fixed window_set_pos and implemented minimization

-Fixed window_set_position(). It used wrong window handler. Some users
still use the wrong one. Why are there 2 handlers in that file?
-Added window_set_minimized() and window_get_minimized().

window_set_visible seems broken and in GM hides the window from both the
screen and the task bar (in Win8 you can only see the window in task
manager). In ENIGMA it just show a black window. To make it work the
same as GM, we need to use ShowWindow() with HIDE parameter instead of a
style.