add real (and imag)

[rcalxrc08]

First I would like to say thank you, I have written my Master Thesis using this package (unfortunately a couple of years ago).

Second,I am trying to use this package to differentiate algos in an agnostic way (meaning that the function has no specialization regarding the number type).
I see that there is no specialization for the implementation of functions real and imag that are implemented for Complex but not for Hyper(Complex).
I think it makes sense to implement them.

Regards,

rcalxrc08

[goedman]

Hi Nicola (@rcalxrc08) , glad HyperDualNumbers.jl was of help for you. Currently I am pretty busy with other projects but if you would be willing to prepare a PR, that would be great!