Message recall window extensions

by <Someone>

(the following text accompanies the patch at <Someone>'s web page)

add more configurability to the new msg_window option of [..]3.4.0.
It allows the configuration option to take an optional parameter to
specify the style of message history display to use.

allows the following configuration options:

msg_window:s - single message (as was the default in 3.3.0)
msg_window:c - combination; two messages in 'single', then as 'full'
msg_window:f - full window; oldest message first
msg_window:r - full window reversed; newest message first

In the event of no parameter being provided,
the patch is compatible with the current 3.4.0 behaviour:
msg_window = 'full'
!msg_window = 'single'
msg_window can be configured for these options in the
Options menu (Shift-O)
msg_window stores the current window type in the non-persistent
iflags structure, which means that savefile/bones files should be
100% compatible with Vanilla, but at the disadvantage that your
customisations to msg_window will be replaced with your
defaults.nh (or ~/.nethackrc) value every time you restart a saved game.
Credits:

The patch draws inspiration (and code snippets) extensively
from <Someone>'s original msg_window patch, [...] as well as <Someone>'s code for reverse ordering implemented until recently in
Slash'em.

dat/opthelp

@@ -74,9 +74,6 @@ timed_delay    on unix and VMS, use a timer instead of sending
                display effect.  on MSDOS without the termcap
                lib, whether or not to pause for visual effect.    [TRUE]
 
-Boolean option if TTY_GRAPHICS was set at compile time:
-msg_window show previous messages in a screen-size window         [FALSE]
-
 Boolean option if USE_TILES was set at compile time (MSDOS protected mode only):
 preload_tiles  control whether tiles get pre-loaded into RAM at the
                start of the game.  Doing so enhances performance
@@ -204,6 +201,12 @@ traps      like dungeon, but for trap symbols
            default:  ^^^^^^^^^^^^^^^^^"^^^^
 windowtype windowing system to be used  [depends on operating system]
 
+Compound option if TTY_GRAPHICS was set at compile time:
+msg_window the type of message window to use:
+           Single      -- One message at a time
+           Full        -- Full window with all saved top line messages
+           Reverse     -- Same as full, but messages printed most-recent-first
+           Combination -- Two single messages, then as full
 
 Some sample options lists are:
 !autopickup,!tombstone,name:Gandalf,scores:own/3 top/2 around