Deprecating manipulability measure methods

[cmower]

@joaomoura24 I am planning to deprecate all the manipulability measure RobotModel methods in #37 . Will this affect your code base?

The reason I want to get rid of them is because (i) it's a lot to maintain, (ii) "manipulability" is somewhat ambiguous since there is other measures than the common Yoshikawa measure, and (iii) it's not such a difficult thing for a user to implement themselves given all the other methods we provide.

I think in the future it would be nice to revisit this and properly implement manipulability measure methods that handle all the cases given a nicer interface. For example, see here.

[cmower]

@joaomoura24 confirmed elsewhere, closing now since this was addressed in #88