Document --check in --help
Fix parameter identification

Names may vary between constructors, but what's important is that the
parameters are in the same position for each constructor. This fix no
longer makes the assumption that the names are the same throughout.

Fixes #1467
Merge pull request #1468 from shlevy/document-check-option

Document --check in --help
Merge pull request #1470 from edwinb/master

Fix parameter identification