This release is mainly for the upcoming FreeBSD package.

* This would crash if <EB> opened more than one file, e.g. EB*.c$.
  The reason is that teco_current_doc_undo_edit() must be called before every teco_ring_edit().
* Unfortunately, this is not reproduceable with
  sciteco --no-profile --fake-cmdline '@EB"foo*.txt"{HK}'
  since the crashes actually happen when printing messages in interactive mode.
  That's why no test case has been added.

* As known from DEC TECO, but extended to convert absolute positions to line numbers as well.
  :^Q returns the current line.
* Especially useful in macros that accept line arguments,
  as it is much shorter than something like
  ^E@ES/LINEFROMPOSITION//+Q.l@ES/POSITIONFROMLINE//:^E-.
* On the other hand, the fact that ^Q checks the line range means we cannot
  easily replace lexer.checkheader with something like
  [:J 0,^Q::S...$ ]:
  Using SCI_POSITIONFROMLINE still has the advantage that it returns `Z` for out-of-bounds ranges
  which would be cumbersome to write with the current ^Q.
* Perhaps there should be a separate command for converting between absolute lines and positions
  and :^Q should be repurposed to return a failure boolean for out-of-range values?
* fnkeys.tes could be simplified.

* The colon modifier can now occur 2 times.
  Specifying `@` more than once or `:` more than twice is an error now.
* Commands do not check for excess colon modifiers - almost every command would have
  to check it. Instead, a double colon will simply behave like a single colon on most
  commands.
* All search commands inherit the anchored semantics, but it's not very useful in some combinations
  like -::S, ::N or ::FK.
  That's why the `::` variants are not documented everywhere.
* The lexer.checkheader macro could be simplified and should also be faster now,
  speeding up startup.
  Eventually this macro can be made superfluous, e.g. by using 1:FB or 0,1^Q::S.

* 13 is now the oldest supported version

* Can be freely combined with the colon-modifier as well.
  :@Xq cut-appends to register q.
* This simply deletes the given buffer range after the copy or append operation
  as if followed by another <K> command.
* This has indeed been a very annoying missing feature, as you often have to retype the
  range for a K or D command.
  At the same time, this cannot be reasonably solved with a macro since macros
  do not accept Q-Register arguments -- so we would have to restrict ourselves to one or a few
  selected registers.
  I was also considering to solve this with a special stack operation that duplicates the
  top values, so that Xq leaves arguments for K, but this couldn't work for cutting lines
  and would also be longer to type.
* It's the first non-string command that accepts @.
  Others may follow in the future.
  We're approaching ITS TECO madness levels.

* Allows storing pattern matches into Q-Registers (^YXq).
* You can also refer to subpatterns marked by ^E[...] by passing a number > 0.
  This is equivalent to \0-9 references in many programming languages.
* It's especially useful for supporting TECO's equivalent of structural regular expressions.
  This will be done with additional macros.
* You can also simply back up to the beginning of an insertion or search.
  So I...$^SC leaves dot at the beginning of the insertion.
  S...$^SC leaves dot before the found pattern.
  This has been previously requested by users.
* Perhaps there should be ^Y string building characters as well to backreference
  in search-replacement commands (TODO).
  This means that the search commands would have to store the matched text itself
  in teco_range_t structures since FR deletes the matched text before
  processing the replacement string.
  It could also be made into a FR/FS-specific construct,
  so we don't fetch the substrings unnecessarily.
* This differs from DEC TECO in always returning the same range even after dot movements,
  since we are storing start/end byte positions instead of only the length.
  Also DEC TECO does not support fetching subpattern ranges.