dd new types, per recent email discussions
Add a GreaterThanLink
Start work on a greater-than link
Implement a c++:greater func for GreaterThanLink
Add documentation
Fix misc errors.
introduce a post-match callback
Fix inconsistent file name
Initial checkin of greter-than unit test
misc cleanup
Merge pull request #805 from linas/greater

start work on GreaterThanLink