parser: use standard functions to parse operators

modified the get operator function to use standard library functions to
parse operators; the input string is temporarily put into a standard
input string stream and read from it

modified the table search function for a single string to take a
standard string and use the standard equal function to compare strings
using the no case compare lambda function (which was moved from the
tester source file to the main header file, and the call from the get
identifier function was modified to pass a standard string)

modified the token constructor for codes to take a standard string
modified the table new token function to take a standard string
(modified callers to pass a standard string)