Camera should follow cursor when using a cursor-based weapon like Girder or Teleport

[trundlr]

Currently the camera continually tries to re-focus on the active grub, but following the mouse makes more sense in this case.

[matekdev]

Done, but it doesn't follow the cursor, I feel it is more natural to allow the user to pan the camera. https://github.com/apetavern/sbox-grubs/commit/fc4dd46740caed5d56959f5ae78797eda28bf92b