Fix parse_rgb() 8-bit to 16-bit color conversion

Fix parse_rgb() 8-bit to 16-bit color conversion
For example, 0xff should convert to 0xffff, not 0xff00.

Fix bar_setup to properly convert the color pixel value to XRenderColor.

Rename swm_screen.c[].color to swm_screen.c[].pixel.

Add new get_ws_idx function.

Use 1 and 0 instead of the Xlib macros 'True' and 'False'.

Fix print_win_geom to not crash when the supplied window is invalid.

Fix windows disappearing on restart.
For now, go back to setting the state iconic in unmap_window.

Add '(void)var;' in functions where var is required but unused.
When using the -Wextra compiler flag, the warning for those variables is
suppressed thereby making it easier to spot warnings that could use our
attention.

Fix type conversion warning in swm_hack.c

Use global atoms where applicable.