xspec patches

Some recent patches from the bugs page :

12.4.0ae	When using the gsmooth or swind1 models, certain combinations of parameters can cause an invalid array access. On 64-bit Linux systems this will cause a crash. Our thanks to Curtis McCully for pointing this out. Report added on Jul 08, 2008.
12.4.0af	When settings have changed through either the xsect or cosmo commands, the model calculations should be immediately updated. (This patch also improves the cosmo command-line parser.) Our thanks to Stefano Bianchi for pointing this out. Report added on Jul 08, 2008.
12.4.0ag	The kerrd and nsa additive models will cause XSPEC to crash in certain cases, the latter primarily on Intel/Mac platforms. Report added on Jul 14, 2008.