Include the UnQlite amalgamation in the module

Makes it as convenient to install (specially on windows) as http://godoc.org/code.google.com/p/go-sqlite/go1/sqlite3, which includes the sqlite3 amalgamation. It also lets the module be sure that it's linking to a thread-safe UnQlite -- maybe the thread safety check could go away.

Also corrected the import in example_test.go, which would always fail when run on a correctly installed `go get`able module. With the fix, builds and passes all tests on win64 and freebsd.