MS-DOS: Add Extended2 symbols to the bundled fonts

This change adds U+2299, U+2601 and U+2980 to the bundled fonts, so
that all symbols specified in the Extended2 symbol set are available.

Also, a few more directives are added to the files, so that FontForge
can load them and display their contents.

sys/msdos/fonts/nh-u16v.bdf

@@ -1,12 +1,21 @@
 STARTFONT 2.1
 FONTBOUNDINGBOX 8 16
-STARTPROPERTIES 3
+STARTPROPERTIES 8
 NOTICE "Additional characters to use with ter-u16v.bdf"
-COPYRIGHT "Copyright 2022 Ray Chason."
+COPYRIGHT "Copyright 2022, 2026 Ray Chason."
+NOTICE "Cloud glyph adapted from the uw-ptty0 font at"
+NOTICE "https://people.mpi-inf.mpg.de/~uwe/misc/uw-ttyp0/"
 NOTICE "NetHack may be freely redistributed.  See license for details."
+PIXEL_SIZE 16
+CHARSET_REGISTRY "ISO10646"
+CHARSET_ENCODING "1"
 ENDPROPERTIES
+CHARS 6
 STARTCHAR tripletilde
 ENCODING 8779
+SWIDTH 500 0
+DWIDTH 8 0
+BBX 8 16 0 -4
 BITMAP
 00
 00
@@ -25,8 +34,34 @@ BITMAP
 00
 00
 ENDCHAR
+STARTCHAR uni2299
+ENCODING 8857
+SWIDTH 500 0
+DWIDTH 8 0
+BBX 8 16 0 -4
+BITMAP
+00
+00
+00
+00
+3C
+7E
+C3
+DB
+DB
+C3
+7E
+3C
+00
+00
+00
+00
+ENDCHAR
 STARTCHAR uppereighth
 ENCODING 9620
+SWIDTH 500 0
+DWIDTH 8 0
+BBX 8 16 0 -4
 BITMAP
 FF
 FF
@@ -47,6 +82,9 @@ FF
 ENDCHAR
 STARTCHAR righteighth
 ENCODING 9621
+SWIDTH 500 0
+DWIDTH 8 0
+BBX 8 16 0 -4
 BITMAP
 01
 01
@@ -65,4 +103,50 @@ BITMAP
 01
 01
 ENDCHAR
+STARTCHAR uni2601
+ENCODING 9729
+SWIDTH 500 0
+DWIDTH 8 0
+BBX 8 16 0 -4
+BITMAP
+00
+00
+00
+00
+00
+0E
+13
+61
+81
+C3
+7E
+00
+00
+00
+00
+00
+ENDCHAR
+STARTCHAR uni2980
+ENCODING 10624
+SWIDTH 500 0
+DWIDTH 8 0
+BBX 8 16 0 -4
+BITMAP
+00
+00
+54
+54
+54
+54
+54
+54
+54
+54
+54
+54
+00
+00
+00
+00
+ENDCHAR
 ENDFONT