Remove use of global process.sass

[xzyfer]

This replaces the global process.sass with proper module exports.
Unfortunately process.sass, although undocumented, is available
to other modules. This patch keeps the existing public API available
until we bump the major.

[xzyfer]

@am11 @andrew do either you have some context as to why process.sass was used in this way?

[andrew]

No idea, I don't remember setting it up, any idea when it was first introduced?

[xzyfer]

@andrew did some digging. Looks like @am11 added the first use of process in #660 and later namespaced using to process.sass in #743.

To the looks of those commits it was just a way to pass information around so it looks safe to remove. Please confirm @am11?

[am11]

Sorry, couldn't sync up earlier as I was travelling the whole past week.
I think the rationale at the time was to create a sass namespace in persistent process object and use it elsewhere.

This new approach is not just pretty ok, it is excellent as the old method was analogous to the practice of frequently appending document object in browser apps, which is discouraged as altering the object layout at runtime is a bad idea (the same reason deleteing object's property is discouraged in JavaScript).

👍

[xzyfer]

Thanks for the background @am11. Hope you enjoyed your travels :)