Robot class is now window aware

Welp, i've been wanting to do this for a long time, so i went for it.

What i did is:
- `_enumerate_windows` returns the winapi window handler along titles.
- Added `get_window_handler` to get the winapi window handler given a window title (loose matching).
- `wait_for_window` returns the winapi window handler of the window that we were expecting (maybe it's better to return a Robot instance refering to that window already).
- Added `get_window_bounds`. This function returns the bounds of the window that the Robot instance represents (`Robot().get_window_bounds()` to get desktop bounds or `Robot("notepad").get_window_bounds()` to do the same with notepad)
- Fixed `move_and_cleck`. Before only moved

I would like to implement tests, but the only thing i come up with is using tkinter to create a GUI where you can test relativeness and colors and stuff, but it wouldnt be too robust.

The `Keys` class is now long, if you want it back the way it was just say it same as If you see anything that could be imporved, or would like to see implemented.

If you are ok AND want to merge the changes, tell me and i'll update the README.