Edit the function key messages as their file

The messages were twelve boxes in a dialog, which meant no labels, no
search-and-pounce set, and no way to read a file somebody published. They are
now the file itself: right-click any function key button under the entry
window, or the two buttons in Config ▸ Keyer and messages, and the text of an
N1MM .mc file opens in a plain editor with Import, Export and Back to the
defaults.

MessageFile reads that format by N1MM's rules. A line starting with # is a
comment; every other line is a label, a comma and the message, with && standing
for one & in a label. Which key a line belongs to is decided by where it is and
nothing else: the first twelve lines are F1 to F12 while running, the next
twelve the same keys while searching, and a file that stops part way through the
second twelve leaves the rest sending what they send while running. A blank line
in the middle is a key with nothing in it, which is what the manual says; the
newline that ends the last line is not, which it does not say, but no .mc file
in the world means its final newline as a message.

Two things fall out of this. The buttons now say what the file says, and they
change when the operator moves between running and searching, so the labels are
the documentation N1MM's manual suggests writing them as. And the search set is
real: ESM's F2 while searching can be a different message from the one it sends
while running, which is how the file was always meant to be used.

Settings keep the file text and carry the twelve stored messages into it on
first read, with the labels this program used then, so nobody loses what they
had typed.

The editor is deliberately a text box rather than a grid of fields: importing,
exporting and editing are then the same thing, and the comments an operator
writes in the file survive being edited here. The telnet window's buttons can
use the same editor later.

Running it caught two: Save as the default button ate the Enter key that a
multi-line editor needs, and the button labels did not follow the move between
run and search until they were redrawn rather than only rebuilt.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -91,8 +91,20 @@ mode stay where they were last typed.
 ### CW
 
 **Config → Keyer and messages** picks `cwdaemon` (a UDP port, usually 6789) or a
-WinKeyer (a serial port), sets the speed, and edits the twelve function key
-messages for CW and for phone. Escape stops sending.
+WinKeyer (a serial port) and sets the speed. Escape stops sending.
+
+The messages are edited as their file, in a plain text editor: right-click any
+of the function key buttons under the entry window, or use the two buttons in
+Config → Keyer and messages. One line per key — the button label, a comma, then
+the message — and a line starting with `#` is a comment. Which key a line
+belongs to is decided by where it is in the file: the first twelve lines are F1
+to F12 while running, and twelve more give the same keys while searching, with
+the ones left out keeping their running message. The buttons say what the file
+says, and they change as you move between running and searching.
+
+This is N1MM's `.mc` format. **Import…** reads a file somebody published for
+N1MM, **Export…** writes one out, and **Back to the defaults** puts the built-in
+messages back.
 
 The macros are N1MM's, spelled the way N1MM's function-key documentation spells
 them, so a `.mc` file written for either program says the same thing. The text