implemented the <^A> command for printing arbitrary strings

* Greatly improved usability as a scripting language.
* The command is in DEC TECO, but in contrast to DEC TECO, we also
  support string building constructs in ^A.
* Required some refactoring: As we want it to write everything verbatim
  to stdout, the per-interface method is now teco_interface_msg_literal()
  and it has to deal with unprintable characters.
  When displaying in the UI, we use teco_curses_format_str() and TecoGtkLabel
  functions/widgets to deal with possible control codes.
* Numbers printed with `=` have to be written with a trailing linefeed,
  which would also be visible as a reverse "LF" in the UI.
  Not sure whether this is acceptable - the alternative would be to strip
  the strings before displaying them.
* Messages written to stdout are also auto-flushed at the moment.
  In the future we might want to put flushing under control of the language.
  Perhaps :^A could inhibit the flushing.

1 files changed, 1 insertions, 1 deletions

diff --git a/TODO b/TODO
index 4ab28df..66f2476 100644
--- a/TODO
+++ b/TODO
@@ -339,7 +339,7 @@ Features:
      just like in Video TECO.
      The DEC behavior could be achieved by always searching till the end
      of the buffer, but excluding all matches beyond the target range.
-   * ^A, :Gq, T, ^T and stdio in general
+   * :Gq, T, ^T and stdio in general
    * :=, :==, :=== to inhibit the linefeed.
    * ^W was an immediate action command to repaint the screen.
      This could be a regular command to allow refreshing in long loops.