Delete regression tests that use removed  structure.
Tweaks to .pdf and .ps generation for mllex and mlyacc.
Condition building of mllex.pdf and mlyacc.pdf on presence of pdflatex.
Avoid updating files that won't change contents with 'make version'.
Only include "Last updated ..." on www.mlton.org pages.
Updates to ReleaseChecklist page.
Do not transform symbolic link targets in release .src.tgz.
Merge pull request #33 from MatthewFluet/pre-201306-release

Further work for 201307?? release.