The new option `app.Suggest` enables command and flag suggestions via
the jaro-winkler distance algorithm. Flags are scoped to their
appropriate commands whereas command suggestions are scoped to the
current command level.
Signed-off-by: Sascha Grunert <sgrunert@suse.com>
Currently, in cases where a flag value is required but not passed and
short-option handling is enabled, a panic will occur due to a nil
pointer dereference. This prevents that situation from occurring,
instead propagating the appropriate error.
