ClassLoaderTest#testRCWB2 / Arithmetic operations of real numbers /Bug fix of CallStack

(1)Added ClassLoaderTest#testRegisterClassWithBinary2()
In progress...(1)
CPUTest#testRCWB2 fails.

(2)Added instructions for real number operations
and created test testRealOperations()

(3)Fixed a mistake in CallStack#getAt(int)
(Refactoring)(Minor)CPUTest:constants

Replaced magic numbers which indicate instructions with constants.
(Refactoring)CallStackTest

Added some tests to CallStackTest.
All tests in CallStackTest succeed.
ClassLoader#getConstant / CPU#call(int)->call(int,int)

(1)Implemented ClassLoaderTest#testRCWB2() (finished)
(2)Added argument newClassID to CPU#call(int)
(Refactoring) Moved CallStack.DataTypeMismatchException to VarEntry

(1)Moved inner class DataTypeMismatchException from CallStack to VarEntry.
(2)Fixed VarEntry#checkDataType(DataType) like what CallStack#checkdataType(VarEntry,DataType) was.
It throws DataTypeMismatchException now.
(3)CallStack#checkDataType(VarEntry,DataType)