Magnitude conversion equation in Atkinson & Boore 1995 GMPE

This pr introduces a magnitude conversion equation in the Atkinson and Boore 1995 GMPE and also replaces existing test tables for Atkinson and Boore 1995 and Boore et al. 1993 GMPEs (originally generated with the hazardlib implementation) with tables provided by the Geological Survey of Canada.

This work is done in the context of the implementation of the 2010 model for Canada.