NeptuneCommon layout

[jamierocks]

NeptuneCommon is laid out by package (under org.neptunepowered.common).

1. interface
The interface package is for all the extra interfaces made for the Mixins. It is further separated by both minecraft and canary interfaces, again by package.

2. mixin
The mixin package is for all the Mixins. It is further separated by both minecraft and canary interfaces, again by package.

2. wrapper
This package is where all the mandatory wrapper implementation goes.