Use Perinci::Sub::Normalize and remove features

- We use Perinci::Sub::Normalize to normalize the function metadata, thereby
  reducing the code (no longer need to normalize Sah schemas in args/result
  ourselves).

- Remove _remove_internal_properties option. This can be handled by
  Perinci::Sub::Normalize if later needed. And turns out we don't need it after
  all.

- The whole modify_meta thing is removed, we'll just normalize the metadata
  prior to use, this is not relatively costly in terms of startup overhead or
  performance.

- We move the conversion of v and default_lang to other dist
  (Perinci-Sub-Convert-{v,default_lang}) to reduce the code in this module.
  Furthermore, those two functionalities are seldom needed.
Release v0.59
Ignore internal properties
Release v0.60