Pretty-print hrmn_spec objects

[jonthegeek]

As a {hrmn} user, in order to easily inspect my harmonization specifications, I would like them to have dedicated print() and format() methods.

Currently, hrmn_spec objects do not have a custom print method, so they display as a simple list. This can be uninformative, especially as specifications become more complex.

Create S3 format() and print() methods for the hrmn_spec class.

• The print() method should display a concise, user-friendly summary of the specification.
• The format() method should provide the underlying implementation for print().

After creating these methods, determine whether hrmn_spec_fct (and any other sub-classes) require their own methods.