command line: split properly at empty line during --import (BMC #7664)

The --import operation was specified as splitting at a blank line and
was meant to work for vCard 3.0 and iCalendar 2.0 files. However, if
the blank line between items used DOS line ends (\r\n) like the items
themselves, then splitting them didn't work because of the literal
match with "\n\n".

This patch introduces a special semantic for the "\n\n" delimiter:
it also matches "\n\r\n" when splitting. This is implemented by
the custom FindDelimiter class.

1 files changed, 9 insertions, 4 deletions

diff --git a/README.rst b/README.rst
index 429e51fe..4df99a29 100644
--- a/README.rst
+++ b/README.rst
@@ -347,10 +347,15 @@ a list of valid values.
   separated by the chosen delimiter string. stdout can be selected with
   a dash.
 
-  The default delimiter are two newline characters for a blank line. This
-  works for vCard 3.0 and iCalendar 2.0, which never contain blank lines.
-  Because items may or may not end in a newline, as a special case the
-  initial newline of a delimiter is skipped if the item ends in a newline.
+  The default delimiter (two line breaks) matches a blank line. As a special
+  case, it also matches a blank line with DOS line ending (line break,
+  carriage return, line break). This works for vCard 3.0 and iCalendar 2.0,
+  which never contain blank lines.
+
+  When exporting, the default delimiter will always insert two line
+  breaks regardless whether the items contain DOS line ends. As a
+  special case, the initial newline of a delimiter is skipped if the
+  item already ends in a newline.
 
 \--import
   Adds all items found in the directory or input file to the