* change droppable option: target option can be a function.
 * update readme: change project website adress.
 * updated documents.
 * changed version.
 * updated project website address.
 + added CHANGES.md.
 * rebuilt.
 * removed jquery extension 'selectText' from unities.js.
 * fixed 'selectText' missing in mindmap.js.
 + added store.js.