New JaxEdit release with version 0.20

[Z.H.]

New JaxEdit release with version 0.20 is out with the following changes:

- Use parse tree as inner data structure in typejax
- list items could contain multiple paragraphs
- able to present and export beamer documents
- able to open and save files in local drives
- able to open and save files in microsoft skydrive
- add main header bar and adjust the appearance

Please visit JaxEdit's new page for more details: https://github.com/zohooo/jaxedit .