implemented program unit and dictionary classes for remarks

added header and source file for base dictionary class
added program unit class with remark dictionary and access function
added encode function to table entry with table access function
added program unit pointer argument to main encode function
modified main encode function to call code encode function if defined
implemented rem encode function to get rem operand index
added rem encode function to rem command and operator table entries
added program unit to tester and passed to test encode input function

added additional remarks to encode test #1, including duplicate comment
strings, and changed expected results to current output (though the
output is not correct)