Replace 'sp+' with '__' around the relation sign in the ref body

[AndreyTalanin]

Summary

Replaced 'sp+' with '__' (requiring at least 1 whitespace) around the relation sign in the ref body, so it's possible to break a line before or after the relation sign for long Ref declarations representing composite foreign keys.

Issue

#470

Lasting Changes (Technical)

• Replaced 'sp+' with '__' around the relation sign in the ref body (line 181)
• Formatted the file on save, trimming trailing whitespaces (actually, unintentionally, can revert it and only leave the first change)

Checklist

Please check directly on the box once each of these are done

• Documentation (if necessary)
• Tests (integration test/unit test)
• Integration Tests Passed
• Code Review

P.S.

Please, let me know if I should continue with this PR and what else needs to be done (adding tests, etc.).

[NQPhuc]

Hi @AndreyTalanin,

Thank you for your interest in improving dbml.

However, we don't intend to make changes to the current dbml parser, as we're in the process of making a new parser for dbml (#458). Therefore, we'll consider your proposal at a later time.