Mark differences between python and C++ style bindings

Created by: anjos

Issue migrated from the bug #104 (closed)

For many functions, we have two different kinds of python bindings: one kind which follows the C++ API (e.g. void f(const BA& input, BA& output)), and one which is more 'pythonic' (e.g. BA f(const BA& input)). These two bindings often share the same python function name. I don't think this is a good strategy, as these sometimes leads to impossible cases when the C++ API has many overloaded functions. I think the function name should reflect this difference. OpenCV strategy was roughly to used two different namespaces (cv for the C like functions, and cv2 for the pythonic one). We could do something slightly different such as appending the function name with something like '_c' or '_cc' to clearly highlight this fact.