recreator: added support for assign and assign list codes

the assign recreate function handles the assign, assign integer, assign
list, assign integer list and assign string list codes (the assign
string needs a separate function because it could be in a mixed
sub-string list assignment); the let recreate support function appends
the LET keyword if the option sub-code is set on the assign token; and
pointers to this function was added to the table entries for these codes

several recreator access functions were moved to the class definition
since they were only one line of code

the expected recreated output files for translator tests 1 to 5 (various
assignment tests) were updated to the expected recreated outputs; all
statements in tests 1 (assignment tests) and 3 (data type assignnents)
are recreated correctly; the statements in the other tests that contain
string and sub-string assignments are not recreated correctly since this
functionality has not been implemented yet