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/sdiff.1

@@ -0,0 +1,102 @@
+.\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.40.4.
+.TH SDIFF "1" "May 2017" "diffutils 3.6" "User Commands"
+.SH NAME
+sdiff \- side-by-side merge of file differences
+.SH SYNOPSIS
+.B sdiff
+[\fIOPTION\fR]... \fIFILE1 FILE2\fR
+.SH DESCRIPTION
+Side\-by\-side merge of differences between FILE1 and FILE2.
+.PP
+Mandatory arguments to long options are mandatory for short options too.
+.TP
+\fB\-o\fR, \fB\-\-output\fR=\fIFILE\fR
+operate interactively, sending output to FILE
+.TP
+\fB\-i\fR, \fB\-\-ignore\-case\fR
+consider upper\- and lower\-case to be the same
+.TP
+\fB\-E\fR, \fB\-\-ignore\-tab\-expansion\fR
+ignore changes due to tab expansion
+.TP
+\fB\-Z\fR, \fB\-\-ignore\-trailing\-space\fR
+ignore white space at line end
+.TP
+\fB\-b\fR, \fB\-\-ignore\-space\-change\fR
+ignore changes in the amount of white space
+.TP
+\fB\-W\fR, \fB\-\-ignore\-all\-space\fR
+ignore all white space
+.TP
+\fB\-B\fR, \fB\-\-ignore\-blank\-lines\fR
+ignore changes whose lines are all blank
+.TP
+\fB\-I\fR, \fB\-\-ignore\-matching\-lines\fR=\fIRE\fR
+ignore changes all whose lines match RE
+.TP
+\fB\-\-strip\-trailing\-cr\fR
+strip trailing carriage return on input
+.TP
+\fB\-a\fR, \fB\-\-text\fR
+treat all files as text
+.TP
+\fB\-w\fR, \fB\-\-width\fR=\fINUM\fR
+output at most NUM (default 130) print columns
+.TP
+\fB\-l\fR, \fB\-\-left\-column\fR
+output only the left column of common lines
+.TP
+\fB\-s\fR, \fB\-\-suppress\-common\-lines\fR
+do not output common lines
+.TP
+\fB\-t\fR, \fB\-\-expand\-tabs\fR
+expand tabs to spaces in output
+.TP
+\fB\-\-tabsize\fR=\fINUM\fR
+tab stops at every NUM (default 8) print columns
+.TP
+\fB\-d\fR, \fB\-\-minimal\fR
+try hard to find a smaller set of changes
+.TP
+\fB\-H\fR, \fB\-\-speed\-large\-files\fR
+assume large files, many scattered small changes
+.TP
+\fB\-\-diff\-program\fR=\fIPROGRAM\fR
+use PROGRAM to compare files
+.TP
+\fB\-\-help\fR
+display this help and exit
+.TP
+\fB\-v\fR, \fB\-\-version\fR
+output version information and exit
+.PP
+If a FILE is '\-', read standard input.
+Exit status is 0 if inputs are the same, 1 if different, 2 if trouble.
+.SH AUTHOR
+Written by Thomas Lord.
+.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), diff3(1)
+.PP
+The full documentation for
+.B sdiff
+is maintained as a Texinfo manual.  If the
+.B info
+and
+.B sdiff
+programs are properly installed at your site, the command
+.IP
+.B info sdiff
+.PP
+should give you access to the complete manual.