Qt extended command selection

Simplify extended command selection under Qt by allowing the
autocomplete subset be one of the choices for its [filter].  That's
the same subset as X11 uses, where #q is unambiguous for #quit
instead of competing with #quaff and #quiver.

Unlike under X11, the player can use [filter] to switch to the full
command set and get access to a few commands which have no useable
key and aren't flagged to autocomplete.  (Mostly obscure wizard mode
commands but #exploremode is in that situation.)

In normal and explore modes, the [filter] button just toggles between
two sets of commands (all normal mode commands vs autocomplete normal
mode commands).  In wizard mode there are four choices and you might
need to click on [filter] up to three times to step through to the
target one among four sets (all commands, all normal mode commands,
autocomplete commands for both normal and wizard, full subset of just
the wizard mode commands).

doc/fixes37.0

@@ -931,6 +931,10 @@ Qt: add Filter, Layout, and Reset buttons to the extended command selector;
 	mode only"; Layout redisplays the grid of command buttons, toggling
 	from down columns to across rows or vice versa; Reset puts both back
 	to their default settings and clears any pending typed input
+Qt: [later] augment extended command selection dialog's Filter to add a
+	fourth subset, those commands which autocomplete when typed for tty,
+	typically commands with no keystroke or only meta character keystroke;
+	that makes Filter useful in normal mode (much shorter list of choices)
 tiles: male and female variations in monsters.txt; tested only with tile2bmp
 	conversion utility so far; also supported by tilemap utility to
 	generate tile.c