implemented get command and added table translate function

the new translate function pointer in the table will contain the
pointer to the function that will perform the translation of a command

the getCommand() gets a command, first determining if the command is
possibly an assignment command (does not start with a command token),
and then calling the commands translate function

the translate function was updated to look at the expression mode
argument and either call the getExpression() function or the new
getCommand() function

added temporary -nt comment line options, which are the same as the -tt
command except use the new translator routines, expanded -n to support
translator input test files with the new translator