Fix constant-conversion Errors

[ajpaulson]

Figure out what was intended for each -Wconstant-conversion error and fix it.

[ajpaulson]

It's mostly mvinch() usage when checking a character at a position.

From what I can find, this is the intended usage - but libncurses chtype is an unsigned long and that means we're implicitly converting.

given that ncurses is still maintained with fixes to match current standards ( http://www.gnu.org/software/ncurses/ ), a more robust method of checking this should be used.