Merge pull request #5 from throrin19/master

get hotfixs
+ add test on getBbox to return directly bbox if element is unchanged
+ add getters/setters for elements for reinit bbox property
+ add contains function
update doc
+ update unit tests
+ update documentation
+ clean usage
package.json 0.3.0
fix code balise
add npm install
Merge pull request #6 from throrin19/release-0.3.0

Release 0.3.0