added unit tests for Poset; also fixed getLUB in order to pass the unit tests
Merge pull request #622 from kframework/segregate-data-in-rewriting

I have a green light from Andrei.
Merge pull request #626 from kframework/invalidateCache

Invalidating cache if the definition is out of date with the latest version of K.
Merge pull request #601 from yilongli/cleanup-KItem-constructor

Cleanup k item constructor
fix kast --parser binary on java backend
Merge pull request #629 from dwightguth/binaryparser

fix kast --parser binary on java backend
add base2string and string2base to string.k
Merge branch 'master' into master2ub2
Merge pull request #632 from kframework/master2ub2

Master2ub2
fix code for computing least sort of KItems
Merge pull request #631 from dwightguth/base2string

add base2string and string2base to string.k
remove exceptions that aren't really error cases
Merge pull request #637 from dwightguth/sets

remove exceptions that aren't really error cases
add ==K for Bags
change to ==Bag
fix return type of String2Base
Merge pull request #635 from dwightguth/kitem

fix code for computing least sort of KItems
Merge pull request #639 from dwightguth/base2string

fix return type of String2Base
add better evaluation trace in case of stack overflow
add naive duplicate recognition to trace algorithm