XSPEC units for setplot wave

In v12.5 we switched the y-axis units under setplot wave to per Hz instead of per Angstrom. Since this has not been universally popular we have added an initialization option to decide between the two cases. This is available as patch 12.5.0t. That and other recent patches can be obtained from the usual place and are summarized below

12.5.0r	Fix needed for all etable model calculations. Our thanks to Roderick Johnstone for pointing this out. Report added on Feb 12, 2009.
12.5.0s	When the both the absori and pexriv models are loaded during the same XSPEC session, whichever model is loaded second will not work properly. Note: this bug originated in version 12.5.0. Report added on Feb 13, 2009.
12.5.0t	This adds an option for choosing Y-axis units when plotting in setplot wave mode. The selection is made by the WAVE_PLOT_UNITS entry, which has been added to the new version of the Xspec.init file. The units may now be specified in Hz (the default for version 12.5.0), or angstroms as they were prior to 12.5.0. This applies to plots of data, counts, and all variants of model and ufspec plots. Report added on Feb 19, 2009.
12.5.0u	Minor code changes mostly to clean up the messages reported when running XSPEC under the valgrind software tool. Report added on Feb 19, 2009.
12.5.0v	Multiplicative model components which are created with the mdefine command should not be multiplied by the energy bin widths. Our thanks to Roderick Johnstone for pointing this out. Report added on Feb 19, 2009.