[DISCUSS] Remove deprecated fields/methods in Gremlin Server

[Stephen Mallette <sp...@gmail.com>]

Every once in a while I peruse JIRA and I take notice of the large body of
tickets around removing deprecated fields and methods in Gremlin Server.
Some of this deprecation occurred along the 3.1.x line of code - I think
it's time to just go through and clean all that up at this point. Here's
the ones I'm looking at:

https://issues.apache.org/jira/browse/TINKERPOP-1010
https://issues.apache.org/jira/browse/TINKERPOP-1046
https://issues.apache.org/jira/browse/TINKERPOP-1049
https://issues.apache.org/jira/browse/TINKERPOP-1296
https://issues.apache.org/jira/browse/TINKERPOP-1465
https://issues.apache.org/jira/browse/TINKERPOP-1526

If you happen to go through them, you'll see that they are all "low-level"
sorts of changes that likely wouldn't affect anyone except perhaps those
who are embedding Gremlin Server in some way. If that's the case, these
folks probably won't have too much trouble sorting out the issues.

I plan to bundle all these changes up into one pull request to master. It
should clean up a fair bit of code to drop all that deprecated stuff.
Please let me know if there are any concerns about killing out this old
code.

Thanks,

Stephen