#11 Add trivial support for connection pooling.

[Vadim Zeitlin]

This simple patch adds a static enableConnectionPooling() method which can be used to, well, enable connection pooling if ODBC layer and the driver support it.

It also adds a new output "connectStringFull" argument to getConnction() which is useful if an incomplete DSN is provided (e.g. without username or password). This is related to pooling as the complete DSN needs to be used to determine whether 2 connections refer to the same data source, hence I include both of these changes in a single patch.

[Vadim Zeitlin]

Patch against 0.2.5