Update RustBCA to 2.0.0: Improvements to Python bindings, code cleanup, simplify Mesh2D input

[drobnyjt]

This will push RustBCA to version 2.0.0 due to breaking changes with the Python bindings and with Mesh2D input.

Fixes: #204 #75

In summary, the following has been added to the Python bindings:

• simplified imports (removed ".pybca")
• updated version numbers
• rotation algorithms for coupling to 3D codes
• benchmarks

The following has been added to the codebase:

• benchmark of attractive-repulsive potentials
• default particle creation methods
• Mesh2D input changed to GetDP style (point- and point-index triangle-lists instead of specifying each triangle by point).