[feature request] Print line in code for lints and diagnostics

[appetrosyan]

Currently melpazoid provides feedback with little granularity, and only up to the offending section.

For example,

- The `;;; Commentary` for this file is much wider than 80 characters

I instead propose the format that states:

- lines [38--40] are wider than 80 characters

Or better yet,

- line 38 is 90 characters, should be less than 80. 
- line 39 is 92 characters, should be less than 80.

This format collaborates with the potential submitter by pointing them to the offending line, as is common with most modern tools/programming languages.