[Proj] GTX format

[Michal Seidl]

Hello,
I am looking forward for +geoidgrids ability in 4.8.0 version. To be 
prepared I have downloaded and compile current development version from SVN.

But I have no idea how to create and install gtx file with geoid data? 
Is there something like geo2bin? To compile text data in binary format?

How to aware proj that new gtx file exists and where?

Thanks for help, Michal