Changes to AZh setup scripts to incorporate 2HDM

- In tanb_grid, mX_to_mA has been put back in for Hhh (when not using 2HDM) as for mssm scenarios the Hhh directory names should still be considered as mH (not as mA)
- General changes to set up the AZh directory structure for 2HDM and to run lxb-xsec2tanb on it
- (disjoint from the 2HDM-related changes) The change in scripts/merge_bin_errors.py was made in order for the code to run correctly even when the name and title of a template in a shape file don't match