cleaner ibtarget interface

libIRDB/include/core/file.hpp

libIRDB/include/core/fileir.hpp

libIRDB/include/core/function.hpp

libIRDB/include/core/ibtargets.hpp

libIRDB/include/core/instruction.hpp

libIRDB/include/libIRDB-core.hpp

libIRDB/src/core/Makefile

libIRDB/src/core/file.cpp

libIRDB/src/core/fileir.cpp

libIRDB/src/core/ibtargets.cpp

libIRDB/src/core/instruction.cpp

libIRDB/src/core/variantid.cpp

libIRDB/test/fill_in_indtargs.cpp

libIRDB/test/fix_calls.cpp

libIRDB/test/read_variantir.cpp