C-bowman/inference-tools: 0.11.0 release

Improved numerical efficiency of the leapfrog update in HamiltonianChain. Fixed some errors so that mass-scaling in HamiltonianChain now works correctly, and renamed the inv_mass keyword argument to inverse_mass. Improved input validation for EnsembleSampler. The inference.gp and inference.mcmc modules were becoming too large, and have now been refactored into sub-packages. Support for importing from the old module names inference.gp_tools and inference.pdf_tools has been removed. The current names inference.gp and inference.pdf should be used instead