Various fixes and improvements.

Added stable hash code for use instead of string.GetHashCode
Fix for Postgres connection leak by adding IDisposable on Query and closing current connection.
Since connection can be changed when transactions are not used, manager can't dispose that connection anymore.
This fixes that problem by explicitly disposing new connection.

On some virtual machines, many listeners were started.
Guard against that behavior by detecting process exit or domain unload and closing listener.

Postgres parsing fixes:
used long instead of int during long parse,
float can be up to 16 chars instead of 14.

Performance fix for bytea:
for is much faster than foreach on large arrays.