Remove redundant non-const member functions

[dpgao]

A number of non-const member functions in the tainted types do exactly the same things as their const counterparts. These non-const functions can therefore be removed without affecting the end-user.

One consequence of the change above is that the rlbox_detail_forward_to_const macro can now be simplified to cover only the cases where non-const member functions actually differ from their const counterparts.

[shravanrn]

@dpgao Just a heads up. I want to be a bit careful merging this to make sure this doesn't break any existing code. So I plan to run some extra tests before merging. Unfortunately, I am traveling for the next two and a half weeks so I can't easily do my extra testing. My tentative goal is to merge this in early February.

Just wanted to keep you posted on this.

[deian]

I think I can review this next week and we can test it in FF tree.

[shravanrn]

Tested on the FIrefox tree. Everything passes. Merging! Thanks @dpgao