Silicon data is not generated with the new approach based on AbiInput and AbinitTask.
 Cleanup abipy.data
 Add example showing how to visualize the convergence of the QP gaps.
 Add GW reference files.
 Example of GW run with AbiInput and workflow a la abinitio
 Temporary hack to make abipy compatible with new version of pymatgen.units
 New wx Widgets I will need for facilitating the use of workflows.
 helper functions to visualize files.
 Put other files under revision control.