PyCNN install notes (for OSX, but also in general)

The guide available at https://github.com/clab/cnn/blob/master/INSTALL.md will mostly get you through installing PyCNN with CNN and Eigen (necessary for CNN)

Here's a few notes

• The PyCNN install guide recommends latest stable version of Eigen, the README file for CNN recommends latest development build. You might have to try both. Either can be installed from http://eigen.tuxfamily.org/ (just unzip and move to cnn folder and rename to eigen and you don't have to mess with mercury/hg)
• The PyCNN install guide hints that you should use python 2.x. This is not a hint Python 2.7 is required for PyCNN

• You can add extra compiler flags in setup.py. On OSX you may need to include the following extra_compile_args(remember the trailing comma. These are function arguments!): [‘-mmacosx-version-min=10.7′,'-std=c++11′,'-stdlib=libc++'],

• You might need to do things several times. Be patient and be stubborn!