Include instructions for only one of Build.PL or Makefile.PL

When both install tools are present, include instructions for only
one, and prefer Build.PL over Makefile.PL like cpan clients do.

Fixes gh-1.
Add some .gitignore stuff
Released 1.200001
Prepare to re-release with an updated compile test
Add MANIFEST.SKIP
Released 1.200002