Error building Caffe with Python 3 support

Caffe can be built with support for Python 2.x. This allows you to invoke Caffe easily from Python code. However, I wanted to call Caffe from Python 3.x code.

• I built Boost with Python 3.x support. I could see that libboost_python3 library files were generated.

• I added this to the normal CMake command that I use to build Caffe: -Dpython_version=3

Sadly, this popped up errors of this type:

libboost_python.so: undefined reference to `PyClass_Type'

This type of error indicates that the Python 2.x Boost library was being used to compile with Python 3.x libraries.