removed Id type changed tag name
if stmt is nil, can't close without panic :(
Merge pull request #3 from NuVivo314/dev

Nice catch. Thank you.
fixed zero value panic
make all internal structures unexported
make condition fields unexported
change Dialect methods to struct type.
added benchmark test, changed mysql driver
Added connection pool
Update example to use connection pool.
Refactor test files
Merge branch 'master' into dev