included missing lemmas
partial progress on proving list head example
checked truth value before pattern expansion
refactoring: adding helper methods to simplify common operations
updated head.spec and included it in regression test
added location and source information to Java backend Rule
revised head_spec
Merge pull request #830 from yilongli/prove-simple-list-head

Prove simple list head
temporary fix for issue 850
Merge pull request #847 from yilongli/add-loc-and-source-info-to-Java-backend-rule

added location and source information to Java backend Rule
Merge pull request #851 from yilongli/temporary-fix-for-issue-850

temporary fix for issue 850
Remove code that calls KompileOptions.Backend.java()
fix substitution filter
fix npe
fix more bugs
fix Java search
add option for old behavior
fix broken tests in tests directory
added the correct callcc-env2.lambda.out
fixed 4_imp++, except regex out for div in lessons 3 and 1