ad-hoc patch to enable dynamic compiling.

Currently jumly compiles just one time, right after page loaded.
We have a document rendering tool which generates DOM tree dynamically.
On integrating with jumly(it's an awesome product!), we need to compile jumly scripts in documents dynamically, too.

_I think_ the patch is does not have a best solution. Exporting a public API would be better.
You can reject this and make your own patch. Anyway what we hope is to have a dynamic compilation feature.
Cheers :)