Socks proxy support

Adds a configuration parameter, proxyEndpoint, which enables socks5 proxy
support in the driver.

This commit also refactors connection information so that it resides
within ClientSession in the Presto client package.
Clarify readme
Catalog can't be empty
Remove dead code

I left some commented out code in typeinfo.d to make it easy to
fix it later. That code is long deprecated so this PR removes it.
There is now a Github issue to tend to the TODOs that are touched
in this PR.
Compile on OSX

This is a *first* step. This does *not* complete the port to OSX.
The changes in this pull request simply make the driver compile, it
does not make it run properly. There are a few more details to work out:
1. The shared static this OSX equivalent of DllMain is currently *not*
executed. This means the runtime is never initialized and the driver
then crashes.
2. There are a few more usages of the long integer type that must be
removed/tended to. Ideally we would find out that there's a 64-bit
iODBC driver, but otherwise we need to deal with this.
Enable compiler warnings
Make fails on windows for unittests