Format 2013/dlowe, new script, rename others etc.

The demo.sh was renamed try.sh to be like the other entries.

The new script diff.sh runs some commands that I had previously added
(to demonstrate the entry) but which would be better in a script.

Renamed sflen.sh (for sparkline file length) to be slflen.sh (for
sparkline file length also).

Updated bugs.md - added more features that the author noted.

Format/typo check README.md file.

This should complete the review of 2013/dlowe.

2013/dlowe/.gitignore

@@ -1,5 +1,8 @@
+1.txt
+2.txt
 dlowe
 dlowe.orig
 fun
+ioccc.txt
 prog.orig
 sparkl