bin/hydiomatic: Add a --dry-run option

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
hydiomatic.utils: Introduce hypformat

hypformat does the same as hypprint, except it returns the string,
instead of printing it. Also reimplement hypprint in terms of hypformat.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
bin/hydiomatic: Implement --diff support

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
hydiomatic.utils: Fix hypprint

(hypprint) can't as easily be reimplemented in terms of (hypformat), so
don't try.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
bin/hydiomatic: Simplify the main option handling logic

Instead of nasty nested ifs, use cond.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>