Extend the message window to cover the whole available vertical space.

Fixes #2091 (it's the solution proposed there), but also fixes #9834 as message window be will redrawn and override the stuff from the previous window. The HP window is also expanded to cover the space between message window and terrain window that is below the HP window.

I recognized the window w_status2 (which is unused with the wide sidebar) causes flickering as it overlays with the other windows, so I excluded it from being redrawn.