Refactoring and cleaning up the code-base.

* cleaning up operator logging
* making operator dependencies explicit in plan operators (:deps op)
* receive-op now accepts channels on its input, so now it knows
 when all of the sub-queries have closed or not.
* making predicates lookup in a map rather than using resolve-ns
so we don't have hackers messing with queries.
* refactoring sub-query generation and query building

.gitignore

@@ -1,4 +1,9 @@
 pom.xml
+*.log
+db/*
 *jar
 lib
 classes
+.cake
+ext
+test/db