brogue-ce: add configuration options for terminal/graphics and macOS
Exposes configuration options 'terminal' and 'graphics', with defaults (false, true respectively) to match existing behaviour
Moves SDL2 deps behind the 'graphics' flag and adds ncurses dep behind 'terminal' flag.
The respective make flags are applied to build for terminal/graphics.
In addition, brogue-ce is bundled into a macOS application when on darwin and graphics are enabled.
authored by amusingimpala75 and committed by Francesco Gazzetta a6915dbe 8ac75907