better function naming at API for "pop" & "popMax"

[spirinvladimir]

Dear Alexander,

During my last update from your branch I've found new function "popMax" for remove rightest node.
So now we have fully completed API for removing rightest and leftest nodes. All possible 2 direction at 2d AVL tree are covered.
I guess name "pop" function has some common with function from JavaScript Array prototype:

1. same name
2. return removed value/item
3. remove item from data-structure's boundary

How to get better understanding what is "popMax" function. Looks like it has same functionality as "pop" but with "Max". What about exactly "Max"? Is it correct logic that "pop" function behavior means "popMin".

I personally fill a gap into semantic size around "pop" and "popMax" functions.