Move gazebo::physics::Inertial to here

[osrf-migration]

Original report (archived issue) by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

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There's mostly math in the gazebo::physics::Inertial class. It would be convenient to move it to ignition-math so that it could be used without linking to the physics library.

[osrf-migration]

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

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pull request #112

[osrf-migration]

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

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addition operator in pull request #115

[osrf-migration]

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

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I've thought about adding a subtraction operator, but the order of operations could be tricky if you subtract multiple small Inertials from a larger Inertial. I'm going to hold off on this for now.

[osrf-migration]

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

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One last feature I'd like to add is the ability to set the rotation of the inertia pose or of the MassMatrix without affecting the moment of inertia matrix in the base frame (ie. the output of MOI()). This is related to this test-case.

[osrf-migration]

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

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• changed state from "new" to "resolved"

MOI rotation added in pull request #121, that should be all the features