Merge branch 'dev-0.2'
warning changes in dev branch
edit readme
data format has been changed
fixed bugs caused by changes of data format
add freemind support to example page, but not implement yet.
support to read a freemind file
support 'position' property in freemind
fix #4
redesign data format, and support freemind format.
publish v0.2b
edit README.md
edit README.md again
resolve #8, support html node with a new properity 'support_html'.
fix #10, let the toggled node stay in the view.
Merge branch 'dev-0.2' into webapp