Pull request: Modifies event-listener setup. Adds additional options.

[chunksnbits]

Hi,

I loved the mixin but since I had a couple of issues getting the mixin to work with dynamic concent, so I made a couple of changes on a fork. Maybe this is also something that is interesting for you (note: my fork was initially based on: https://github.com/ganeshp0001/react-sortable-mixin). The following changes were made:

• Move event handling to list-mixin, i.e., makes it easier to handle dynamic content and minimizes the amount of event-listeners attached (one on document vs. n for every child), which should also improve performance for larger lists
• Adds option to limit movement to x- / y- axis
• Adds option to specify a class-name to be added to the dragged item
• Adds option to specify a class-name to be added to the placeholder
• Adds option to specify the z-Index to be set for the dragged item

I have one issue, I am currently not happy with. Maybe you have an idea how to solve this better:

• Right now I register the list-items using their reactid. This does not seem to be the best solution, but I found no better way to communicate between the components without demanding additional markup / attribute for using them. This also causes the tests to fail right now.

Have a look and if you are interested or require additional changes, feel free to contact me.

Greetings,
Daniel