Renaming/cleanup before the next release

Copied over from Github.

• drop Local from integrands, possibly other stuff in local/
• drop Localizable from LocalizableBilinearFormBase, possibly other stuff (localizable means we can walk over the grid, kind of the base assumption in dune)
• LocalizableBilinearFormBase -> BilinearForm
• MatrixOperator should not be a grid walker, rather create one in assemble and otherwise be merged with/derive from the local assembler
• same goes for VectorFunctional
• rename LocalizableOperator -> Operator
• update/add bilinear form like localizable operator, possibly derive from operatorinterface
• check if we need L2VolumeVectorFunctional
• rename with_source and other similar occurrences to with
• derive local operators from local functionals (Issue #15)

in dune-xt:

• make prefix_ a public prefix member
• in WithLogger: drop logging_prefix argument, use logging_id as prefix, use id for logging propagation (this.logger.prefix + '*' + other.logger.prefix), use own class name instead of id elsewhere (LOG_(debug) << "GridFunctionInterface.foo(" << ...)
• use GridFunctionInterface instead of GridFunction again in integrands and check lifetime of temporaries
• add print to Functions and LA namespace, circular dep not clear yet