Added student's t distribution to contrib/statsLib
Combined dnbinom.cpp and dnbinom_eco.cpp, all now named dnbinom. Added dzinbinom.cpp zero inflated negative binomial negative log likelihood.
Fixed statsLib.h so that it contains the function and class declarations for the implemented functions. Removed redundant #include statements. Added some functions including vcubic_spline, dunif, dinvgamma, dmvlogistic, eplogis, mutifan, and rmvlogistic. Created makefiles for g++ and Visual studio (cl) compilers. These have both been tested on Windows. g++ works through mingw comand shell and cl works through the Visual studio command prompt. Still need to get dbinom_eco and dbinom_eco_zi working.
Added build files for contributed libraries.To use:$ make --directory=scripts/configure$ ./configure$ make$ make contrib
Contributed libraries from Steve Martell --directory contrib/statslib