Improve and fix 2011/fredriksson/try.sh

The script now writes the output to a file (via tee(1)) and uses diff -s
on the file and fredriksson.c. It also fixes a problem where if one were
to hit space after the prompt (lines would be merged) rather than
enter/return.

Fixed shellcheck warning (no need to ignore it).

2011/fredriksson/.gitignore

@@ -5,6 +5,7 @@ ag.c
 *.dSYM
 fredriksson
 fredriksson.orig
+fredriksson.txt
 indent
 indent.c
 indent.o