Prevent global namespace polution with IIFE
Shorter variable name for previous leaflet methods
Fix setZoomAround wrong variable name bug
Prefix source file with leaflet
Correct source location in example page and test module
Move css styles from example page to separated file
Rename style.css -> styles.css
Reintroduce leafletActiveAreaPreviousMethods global variable

   Since this variable is global, it’s better to have a longer name to
   avoid collision.
Remove some spaces
Merge branch '11th-11th-edit'