Fix a major backchaining bug
Filter out some semantically meaningless rule applications
Merge github.com:opencog/opencog
Merge pull request #385 from linas/master

rearrange cython tests
Minor CMakefile cleanup: no one uses XML
formulas fully functional
Merge branch 'master' of github.com:opencog/opencog
Merge pull request #386 from keyvan-m-sadeghi/master

Interval Algebra, formulas done
Fixed warnings in planner.
Merge pull request #387 from shujingke/planner

Fixed warnings in planner.
Merge github.com:opencog/opencog
fix more minor Rule bugs
Merge pull request #389 from jadeoneill/master

PLN doesn't get errors and the chainers seem to work
unlock before issuing signal
unlock when sending the remove signal too.