New asn1 compiler option

[Tomas Johansson]

I've added a new compiler option to the asn1 compiler called macro_name_prefix.
It works similar to the existing option record_name_prefix, but for
macros instead.

It is needed when multiple protocols that contains macros with
identical names are included
in a single module.

I've also added the existing record_name_prefix option to the
documentation since it was missing.

Couldn't find any tests in the asn1 application, but I used the asn1
files in the
examples/ subdir to verify that my changes have the desired effect.

git fetch git://github.com/jotsen/otp.git asn1_macro_prefix