uuid-ossp extension for pg-mem

[pomgui]

Hi Oliver,

First I must say what an awesome work you made!

On my projects with PostgreSQL, I use UUIDs all the time, so for me uuid-ossp extension is not something optional, but I totally understand why you designed like that.

I think there are many projects depending on that extension, so I tried to alter your code to "lazy load" an embedded uuid-ossp module when create extension "uuid-ossp" is executed, but I stopped when I noticed there were multiple files I should change, so it was not as straightforward as I initially imagined.

So I changed my strategy and I've just created an external npm pg-mem-uuid-ossp package that provides all the functions the original postgresql uuid-ossp extension does, in hopes that it might be useful to others.

I also hope that the name "pg-mem-uuid-ossp" is ok for you.