Replace rbtree implementation

[condret]

Current rbtree implementation has some issues with UAF after using the delete function.
It would be more desirable to fix that, but let's face it: Nobody in the dev-community has the gigachad brain to understand this compactly written piece of code in all details and it's effectively unmaintainable for us.

https://github.com/leiless/jw_rbtree this implementation looks much more simple, clean and seems easier to understand.

Befor start porting it, here are some rules:

• no single character varnames
• keep complexity as low as possible

I'll do the port, @radare pls do the review later

[condret]

https://github.com/radareorg/jw_rbtree/tree/master/src

[trufae]

Thats merged. Good job

[trufae]

Now its time to replace the old one

[condret]

I set the milestone to attic, bc replacing all occassions of the old api may take a looooong time