fix for unification.k
Updated ! with ?
Merge branch 'unified-builtins2' into issue-607
Enforcing failback to syntactic equality for set difference and free vars computation.
fix some bugs in ListBuiltin
fix copyright
Merge pull request #653 from kframework/issue-607

Issue 607
fix bug with stdout
fix more bugs in ListBuiltin code
fix #stdout function in java backend
If I can't find a LUB for the rewrite, then use K. This is a temporary fix.
Merge pull request #666 from dwightguth/stdout2

fix #stdout function in java backend
Merge pull request #667 from kframework/fixParserNPE

If I can't find a LUB for the rewrite, then use K. This is a temporary fix.
Merge pull request #661 from dwightguth/confvar

fix some bugs in ListBuiltin
Merge remote-tracking branch 'origin/unified-builtins2' into ASTNode-implements-List
override with Object.hashCode and Object.equals in ASTNode