Added NEQ to lie_group_base (Issue #316)

[MarshallVielmetti]

See Issue #316

Added NEQ operator overload to lie_group_base and some tests.

[artivis]

Hi, thanks for the contribution!

Would you kindly add:

• the inequality operator to the TangentBase class (see here) so that it is at parity with the LieGroupBase.
• a couple 'expect's to the template test so that all groups/tangents are covered by the test? You can add them directly in the existing evalIsApprox test (see here).

I'll look at the failing tests as they are currently failing for reasons unrelated to this pr.

[MarshallVielmetti]

Of course--should be updated!

[artivis]

Thanks for the update 👍 .
I'll merge this PR once I get #319 through.