Replace bonded interactions cython interface

[RudolfWeeber]

Bonded interactions should be managed by the script interface and the hand-crafted Cython code should be removed.

Steps:

• Wrap the bonded interaction parameter store by a map-like container

  • should support at() and insert() and contains() as in std::unordered_map
  • and an additional insert() which auto-generates a free key (as we would like to avoid manual bond id handling in the future)

• Reading clients such as the bond loop should probably only have const access

  • convert read access throughout Espresso source to use bonded_ia_params.at()
  • adapt set_bonded_ia_params() in bonded_interactions/bonded_interactions_utils.hpp

• Remove MPI broadcasting of bonds

• Write an ObjectMap analogue to the script interface ObjectList which wraps an associative container:

  • add() method takes a KeyType and a ManagedType
  • remove() takes a KeyType

• Write Python bindings for the ObjectMap

  • __getitem__(), __iter__(), and dictionary-related friends

• Implement the script interface BondedInteractInteractionsMap

  • making use of ObjectMap, otherwise analogous to Constraints or LBBoundaries

• Write script interface classes for Espresso's bonded interaction classes

• @script_interface-register the classes BondedInteractionsStore and the bonded interaction script interface classes in Python