Support for interfaces and for Go 1.6

This patch is useful for playing with reflect. You could consider this as a bugfix, since the type checked in the type switch, was not that of the underlying type. I added a test to illustrate my point.

Since I was testing this in Go 1.6, which got stricter in terms of pointers in Cgo, I commented out some parts of the code and removed examples_test.go.

Signed-off-by: Tibor Vass [email protected]