StringUtils - duplicate description of operations

[SuperMauro1966]

A lot of operations have the same description.

It would be nice if there would be a description of the meaning of input/output parameters and of their value domains (example rightPad use a node char that need to be set to the encoding character set, but this is not indicated in the documentation).

Another nice improvement would be to append to each instruction a little example.

[klag]

@thesave I think there is a bug in the generator