canonicalized builtin data structures
renamed Term#hasCell to Term#isMutable; fixed BuiltinMap/Set/List#computeMutability()
reimplemented KSequence without using persistent data structure for now; cleaned up useless methods
fixed KSequence#isConcreteCollection
reimplemented KList
reimplemented CellCollection
updated Guava library to 17.0 to get a fix in the api of Multimaps
fixed failing prover tests
fixed a bug introduced during refactoring
Merge branch 'master' into canonicalize-collections-in-builder-pattern-part1

Conflicts:
	src/javasources/KTool/src/org/kframework/backend/java/symbolic/PatternMatcher.java
	src/javasources/KTool/src/org/kframework/backend/java/symbolic/StepRewriter.java
Merge branch 'master' into canonicalize-collections-in-builder-pattern-part1

Conflicts:
	src/javasources/KTool/.classpath
	src/javasources/KTool/buildjava.xml
Merge pull request #933 from yilongli/canonicalize-collections-in-builder-pattern-part1

Canonicalize collections in builder pattern