interface stability guarantees

currently there is, approximately zero stability guarantees, we can change anything at any time, functions might disappear, etc.

Given that admins might use `gxadmin` in pipelines I think I should implement something that will give them more stability. The current idea is something like:

```
query_blah-blah_v1() { ... }
query_blah-blah_v2() { ... }
```

which could be called as `query blah-blah` (for the 'latest' version) and maybe `blah-blah_v2` for a specific version? When you're writing a pipeline that you want to include a specific version in you'd then use the versioned identifier of the function name, and we'd be free to update/change behaviour of functions.

And for the 'older' version of these functions we'd just move them to a 'graveyard' since we'll never touch them again.