Consider implementing strict/non-strict parser modes

[Davidde94]

Strict parser mode can be used to test standard compliance and report issues.

Non-strict mode can be used in real-world applications to deal with imperfect clients and servers.

[Davidde94]

This will probably be best implemented if we move away from the static methods to instantiate a configurable type.

[danieleggert]

This would be great to have such that we can report issues to various server implementations as we find them.

The strict mode doesn’t have to be perfect.