Compute CR0, CR1, CR2 cluster robust standard errors with empirical-degrees of freedom adjustments

Includes syntax that computes the standard error adjustments and degrees of freedom adjustments. Syntax is not optimized for speed but included for readers who want to follow through the syntax step-by-step.

To uninstall: Extensions -> Utilities -> Custom Dialog Builder (Compatability Mode). Select File -> Uninstall … Select the Cluster_Robust_Reg_compatibility