Removed "Stata 202.do".

It isn't that useful currently, since there is just one module.
Moved {HEAD1} out of "Shared directives.do".
Updated links for 205.
Updated introduction to 205.
"Do to SMCL.do" now supports clickable Mata commands.
Updated Mata module.
Merge pull request #2 from mwhite-IPA/master

Updated Mata module for 202.