use hashing for large name lookups, create Collections class

.../src/com/oracle/truffle/r/nodes/builtin/base/Sample2.java

...n/src/com/oracle/truffle/r/nodes/builtin/base/Unique.java

.../truffle/r/nodes/access/vector/SearchFirstStringNode.java

...runtime/src/com/oracle/truffle/r/runtime/Collections.java

...fle.r.runtime/src/com/oracle/truffle/r/runtime/Utils.java

...est/src/com/oracle/truffle/r/test/ExpectedTestOutput.test

...oracle/truffle/r/test/library/base/TestSimpleVectors.java