Signed off contributors

Added in BSD license to files

Partially fixed qualifying the empty set constant with its type
Merge branch 'devel-smt' of github.com:Whiley/WhileyCompiler into devel-smt
Changed copyright author
Merge pull request #413 from hjwylde/devel-smt

Pulling your changes.  Sorry they didn't make the latest release, but they'll be in v0.3.29, to be released next week!