Fix remove hotfixes/hacks etc. once OpenSim 4.5 is released

[adamkewley]

• https://github.com/ComputationalBiomechanicsLab/opensim-creator/issues/383
• https://github.com/ComputationalBiomechanicsLab/opensim-creator/issues/524
• https://github.com/ComputationalBiomechanicsLab/opensim-creator/issues/523
• https://github.com/ComputationalBiomechanicsLab/opensim-creator/issues/517
• https://github.com/ComputationalBiomechanicsLab/opensim-creator/issues/515
• https://github.com/ComputationalBiomechanicsLab/opensim-creator/issues/382