Add setters for single drawables (setLeftDrawable, setTopDrawable, etc)

[a-tolstykh]

[MisterFruits]

I'm not sure if this is related but I'm struggling to programatically set a drawable to a TextViewRichDrawable (I'm inside a RecyclerView and need a different drawable for each view).

Can you confirm that my use-case is related to this issue or should it work already ?

Edit: I finally managed to display images using setCompoundDrawables(Relative)WithIntrinsicBounds instead of setCompoundDrawables but now the size set in the XML is not taken into account... Maybe I should open another issue.

Edit 2: Eventually I tested the #18 code and using the new setDrawables method I managed to fix my issue. I would recommend to take a look at the PR and integrate it.

Cheers!