New arch 1st step: add a plugin name

[Indigo744]

This is a first step to the new architecture (see #117).

It adds:

• a variable containing the plugin name "mapael"
• a check against multiple instanciation (and throw error if trying to instanciate multiple time)
• allow external access to current instance on element through $.data()
• a class mapael to the element on which mapael is defined

It removes:

• the return statement that was useless

[neveldo]

What is the purpose of adding the plugin name as a class name on the element ?

[Indigo744]

This allows the plugin to be deterministic:

• declaring externally that mapael is assigned to this element
• allow specific CSS customization aimed at mapael (without fearing name collision)

[Indigo744]

About the second point, we will be able to define the CSS for mapael.
Example: the .tooltip class. There is high chance this name is already used on a website, or through a framework, with different parameters.
Hence, using .mapael .tooltip will allow specific selectivity.

[neveldo]

Hello,

Thank for the explanation, it's ok for me. However, regarding the second argument, currently, nothing prevent the user from adding a custom class name on the container in order to allow specific selectivity in the CSS, this is why I was curious about the purpose of the class.