latest buildfarm client release

I have just released version 4.16 of the PostgreSQL Buildfarm client

It can be downloaded from
<http://www.pgbuildfarm.org/downloads/latest-client.tgz>

Several bugs have been fixed, and there are these non-trivial changes:

* capturing of TAP test logs
* bin check enabled on Windows
* rm_worktrees feature
* an experimental module to run Sepgsql tests
* try database shutdown following a start failure
* report all PGBuild module versions to server

rm_worktrees is enabled by putting this in your config file:

rm_worktrees => 1,

The effect is that at the end of a run the checked out work tree is
removed, leaving just the git repository, which in turn might be mostly
linked to your HEAD branch if you use the git_use_workdirs option.
Before a run, the work tree will be checked out again. The net effect is
a significant saving in space used. with these two options, the
additional space for each branch except when it's actually building is
reduced to less than 30Mb. On crake, the git mirror, branch trees and
cache now come in at about 1.5Gb. That's a lot less than it used to be.

Shutdown after a start failure tries to remedy a situation where we try
to start the server, and don't detect that it has started, but it has in
fact started. So now if we get a failure we try to shut down any server
that might have started, just in case. This change is possibly redundant
given the recent change where postgres detects that its data directory
has disappeared and shuts down when it has, but it's probably worth
having anyway.

cheers

andrew