src/reg1.cpp: Added Doxygen documentation for the mmscore_regression() function, as well as a description of what the function does. Includes minor rewrite of the actual code, renaming variables and removing one call to .transpose().
Also changed and added some (partial) Doxygen documentation to other functions.

doc/ProbABEL_manual.tex: Added a number to an equation I reference in the Doxygen documentation



git-svn-id: svn://svn.r-forge.r-project.org/svnroot/genabel@1725 edb9625f-4e0d-4859-8d74-9fd3b1da38cb