Fix a major backchaining bug
Filter out some semantically meaningless rule applications
Merge 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.
Merge pull request #390 from linas/master

signals should be delivered with locks unlocked.
Refactor so backchaining can handle all the special cases (maybe)
grab lock during destruction
Merge pull request #391 from linas/master

grab lock during destruction
Test backward chainer
PLN Rule names are less ambiguous
Merge pull request #392 from jadeoneill/master

Fix backward chainer
Add diagram of a time interval
Merge pull request #395 from linas/master

Add diagram of a time interval