feat: use es6 module

[mjeanroy]

@sapegin Here is a PR for #58.

I did not want to make lot of changes so:

• I just copy the jquery.mosaicflow.js to a new jquery.mosaicflow.m.js using ES6 import.
• The jquery.mosaicflow.js is just the result of babel executed on jquery.mosaicflow.m.js file.

[sapegin]

I’d put all generated files to dist folder. As a side effect you could avoid this ugly .m.js.

[mjeanroy]

@sapegin That was my first idea, but people using the library directly (i.e without a module bundler, or without something reading the main entry point) will need to update the path to the jquery.mosaicflow.js to point to the dist folder (probably not a big problem since it will be very easy to fix).

I also suggest to move the jquery.mosaicflow.m.js to src/jquery.mosaicflow.js because keeping jquery.mosaicflow.js at the root will not throw an error for people currently pointing to it.

What do you think?

[sapegin]

I don’t know how many people still use the library but I won’t mind path change. So src + dist and no .m :-)