`wmouse_trafo` should take a `*const WINDOW`

If you look up wmouse_trafo, you will see that it should take a const WINDOW* https://linux.die.net/man/3/mouse_trafo. Here are the places that take it mutably:

ncurses-rs/src/ll.rs

Line 378 in 5cefed9

    
           pub fn wmouse_trafo(_:*mut WINDOW,_:*mut c_int,_:*mut c_int,_:c_bool) -> c_bool;

ncurses-rs/src/lib.rs

Line 1997 in 5cefed9

    
           pub fn wmouse_trafo(w: *mut WINDOW, y: &mut[i32], x: &mut[i32], to_screen: bool) -> bool

I believe the correct thing to do is replace *mut WINDOW with just WINDOW as used in the other functions in these files.

Thanks! This is now published.