KL tracking

This tar file allows one to recreate plots found in paper "Energy tracking in a turbulent channel flow using Karhunen-Loe've analysis" to be submitted to Journal of Fluid Mechanics. After download, detar with command "tar -xzf KL_tracking.tar.gz". Go to directory "notebooks" and run both notebooks in Jupyter notebook. Parameters can then be changed to look at different wavenumbers, window size, etc. Version 2: Modified calculation of transfer_in and transfer_out