Camera: update matrixWorldInverse in updateWorldMatrix() method

[DavidPeicho]

For people not using matrixAutoUpdate, and using updateWorldMatrix(), it's possible to end up in a case where the camera matrixWorldInverse is actually out-of-date.

This PR makes the Camera class override the updateWorldMatrix().

[mrdoob]

Thanks!

[riebling]

I hope this has nothing to do with (we're still trying to track down what causes!) a predicament where Firefox-webxr on an iOS device, using A-Frame in AR mode, on top of three.js reports it's camera world coordinates all backwards: move the device down, Y increases. Move it to the left, X increases. Move it away from you, Z increases. All the 'inverse' of what we expect :) Probably just a coincidence. Carry on, & thanks for the good work

[Mugen87]

WebXRManager does not use Camera.updateWorldMatrix() so it seems what you report is unrelated to this change.