[Array] .map() function should provide 3 arguments to the callback - the item value, item index and the traversed array
[Array] validate second and third parameters of callback function in .map()
Added state of supported boards
Merge pull request #5 from ebirger/array_map_params

Array map params
Update README.md
documentation
Merge branch 'master' of github.com:espruino/Espruino