py/lexer: Simplify and reduce code size for operator tokenising.
By removing the 'E' code from the operator token encoding mini-language the tokenising can be simplified. The 'E' code was only used for the != operator which is now handled as a special case; the optimisations for the general case more than make up for the addition of this single, special case. Furthermore, the . and ... operators can be handled in the same way as != which reduces the code size a little further. This simplification also removes a "goto". Changes in code size for this patch are (measured in bytes): bare-arm: -48 minimal x86: -64 unix x86-64: -112 unix nanbox: -64 stmhal: -48 cc3200: -48 esp8266: -76