Naming convention

[hannorein]

The naming of variable and function names really needs to be made more consistent. It's all over the place right now.

• Given that most people probably use the Python API, we should follow PEP8. Specifically: function names and variables use lowercase, with words separated by underscores as necessary to improve readability.
• The C equivalents should mostly follow Python.
• Structures in c do not use typedef. They are always referred to struct, e.g. struct reb_simulation.
• Structure names in C start with the prefix reb_ followed by small letters, words are separated with underscores, e.g. reb_hash_pointer_pair.
• Class names use the CapWords convention in python and ignore the reb_ prefix. reb_simulation <-> Simulation, reb_simulationarchive <-> Simulationarchive, reb_hash_pointer_pair <-> HashPointerPair
• Only use verbs in a function name if the function changes the state.
• Simulationarchive is one word. _simulationarchive_ in c and Simulationarchive in python.
• Variables describing memory allocation have names such as N_allocated_collisions.
• Function names should start with the main object they operate on: reb_simulation_move_to_com().
• Structure names used in function names do not use CapWords, e.g. reb_simulationarchive_take_snaphot()
• Function names should have a name such that switching between C and python becomes trivial: reb_simulation_energy() <-> rebound.Simulation.energy().
• Avoid "set" and "get" in function names. Instead of reb_get_com() use reb_simulation_com().
• Memory management: create, allocates and initializes an object. free frees the memory of an object (and all the objects it owns). init does not allocated an object itself, but merely initializes it with default values. The verb follows the object, e.g. reb_simulation_create().
• We won't provide deprecation warnings.

[hannorein]

Trying things out over on the namingconvention branch.