Crosshair resource

When true, this causes the emulator to display a crosshair cursor. The implementation is different on each interactive emulator, but the basic idea is to highlight the entire row and column containing the cursor. The crosshair does not blink, even if the cursorBlink resource is true.

On x3270, c3270 and wc3270, the crosshairColor resource defines the host color used to display the crosshair cursor.