Truffle API cleanup: Reduce the visibility of classes and constructors that are not intended to be instantiated by guest language implementations; provide abstract class RootCallTarget as a CallTarget to a RootNode

--HG--
rename : graal/com.oracle.truffle.api/src/com/oracle/truffle/api/impl/DefaultCallTarget.java => graal/com.oracle.truffle.api/src/com/oracle/truffle/api/RootCallTarget.java
Refactoring and cleanup of Simple Language (more to come soon)

--HG--
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/SimpleLanguage.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/SLMain.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/builtins/BuiltinNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/builtins/SLBuiltinNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/builtins/PrintBuiltin.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/builtins/SLPrintBuiltin.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/builtins/TimeBuiltin.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/builtins/SLTimeBuiltin.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/BinaryNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/SLBinaryNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/TypedNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/SLExpressionNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/FunctionRootNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/SLRootNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/SLNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/SLStatementNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/SLTypes.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/SLTypes.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/CallNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/call/SLCallNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/BlockNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/controlflow/SLBlockNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/BreakNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/controlflow/SLBreakNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/ContinueException.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/controlflow/SLContinueException.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/ContinueNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/controlflow/SLContinueNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/FunctionBodyNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/controlflow/SLFunctionBodyNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/IfNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/controlflow/SLIfNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/ReturnException.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/controlflow/SLReturnException.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/ReturnNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/controlflow/SLReturnNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/WhileNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/controlflow/SLWhileNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/LessThanNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/expression/SLLessOrEqualNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/LogicalAndNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/expression/SLLogicalAndNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/ReadLocalNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/local/ReadLocalNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/ReadArgumentNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/local/SLReadArgumentNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/WriteLocalNode.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/local/WriteLocalNode.java
rename : graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/SLNodeFactory.java => graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/parser/SLNodeFactory.java
Use source and expected output files to test Simple Language, instead of individual JUnit tests with the source and expected output as strings
Fix Eclipse formatter issues
Fix SL unit test directory
updated mx/projects for new Okra version