milestone: complete rework of rtrafo()
with explicit formulas for the inverses of C, Ga, t;
deprecated gnacopula();
bug-fix in htrafo()

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/nacopula@1127 edb9625f-4e0d-4859-8d74-9fd3b1da38cb