D7: editor multi-cursor support

Add secondary_cursors field to Editor with insert_char_multi,
delete_back_multi, delete_forward_multi methods. Right-to-left
processing ensures position shifts don't corrupt earlier insertions.

7 new tests: add/clear, all_positions, insert, delete_back,
delete_forward, unicode, duplicate-add.

local/recipes/tools/diffutils/source/man/diff3.1

@@ -0,0 +1,100 @@
+.\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.40.4.
+.TH DIFF3 "1" "May 2017" "diffutils 3.6" "User Commands"
+.SH NAME
+diff3 \- compare three files line by line
+.SH SYNOPSIS
+.B diff3
+[\fIOPTION\fR]... \fIMYFILE OLDFILE YOURFILE\fR
+.SH DESCRIPTION
+Compare three files line by line.
+.PP
+Mandatory arguments to long options are mandatory for short options too.
+.TP
+\fB\-A\fR, \fB\-\-show\-all\fR
+output all changes, bracketing conflicts
+.TP
+\fB\-e\fR, \fB\-\-ed\fR
+output ed script incorporating changes
+from OLDFILE to YOURFILE into MYFILE
+.TP
+\fB\-E\fR, \fB\-\-show\-overlap\fR
+like \fB\-e\fR, but bracket conflicts
+.TP
+\fB\-3\fR, \fB\-\-easy\-only\fR
+like \fB\-e\fR, but incorporate only nonoverlapping changes
+.TP
+\fB\-x\fR, \fB\-\-overlap\-only\fR
+like \fB\-e\fR, but incorporate only overlapping changes
+.TP
+\fB\-X\fR
+like \fB\-x\fR, but bracket conflicts
+.TP
+\fB\-i\fR
+append 'w' and 'q' commands to ed scripts
+.TP
+\fB\-m\fR, \fB\-\-merge\fR
+output actual merged file, according to
+\fB\-A\fR if no other options are given
+.TP
+\fB\-a\fR, \fB\-\-text\fR
+treat all files as text
+.TP
+\fB\-\-strip\-trailing\-cr\fR
+strip trailing carriage return on input
+.TP
+\fB\-T\fR, \fB\-\-initial\-tab\fR
+make tabs line up by prepending a tab
+.TP
+\fB\-\-diff\-program\fR=\fIPROGRAM\fR
+use PROGRAM to compare files
+.TP
+\fB\-L\fR, \fB\-\-label\fR=\fILABEL\fR
+use LABEL instead of file name
+(can be repeated up to three times)
+.TP
+\fB\-\-help\fR
+display this help and exit
+.TP
+\fB\-v\fR, \fB\-\-version\fR
+output version information and exit
+.PP
+The default output format is a somewhat human\-readable representation of
+the changes.
+.PP
+The \fB\-e\fR, \fB\-E\fR, \fB\-x\fR, \fB\-X\fR (and corresponding long) options cause an ed script
+to be output instead of the default.
+.PP
+Finally, the \fB\-m\fR (\fB\-\-merge\fR) option causes diff3 to do the merge internally
+and output the actual merged file.  For unusual input, this is more
+robust than using ed.
+.PP
+If a FILE is '\-', read standard input.
+Exit status is 0 if successful, 1 if conflicts, 2 if trouble.
+.SH AUTHOR
+Written by Randy Smith.
+.SH "REPORTING BUGS"
+Report bugs to: bug\-diffutils@gnu.org
+.br
+GNU diffutils home page: <http://www.gnu.org/software/diffutils/>
+.br
+General help using GNU software: <http://www.gnu.org/gethelp/>
+.SH COPYRIGHT
+Copyright \(co 2017 Free Software Foundation, Inc.
+License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
+.br
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+.SH "SEE ALSO"
+cmp(1), diff(1), sdiff(1)
+.PP
+The full documentation for
+.B diff3
+is maintained as a Texinfo manual.  If the
+.B info
+and
+.B diff3
+programs are properly installed at your site, the command
+.IP
+.B info diff3
+.PP
+should give you access to the complete manual.