Refactor impargs code.
Refactor impargs code.

This should preserve semantics exactly.
In the compute_implicits family of functions, I changed the
name of the pushed rel to not be fresh, but the env isn't passed
to find_displayed_name_in, and shouldn't affect whd_all.

Zimmi48/coq,coq/coq,silene/coq,ppedrot/coq,JasonGross/coq,JasonGross/coq,ppedrot/coq,ppedrot/coq,silene/coq,gares/coq,gares/coq,coq/coq,Zimmi48/coq,letouzey/coq-wip,Matafou/coq,letouzey/coq-wip,ejgallego/coq,gares/coq,Matafou/coq,maximedenes/coq,ppedrot/coq,ejgallego/coq,ejgallego/coq,ejgallego/coq,ppedrot/coq,letouzey/coq-wip,maximedenes/coq,SkySkimmer/coq,gares/coq,letouzey/coq-wip,maximedenes/coq,maximedenes/coq,SkySkimmer/coq,letouzey/coq-wip,Matafou/coq,Zimmi48/coq,JasonGross/coq,maximedenes/coq,silene/coq,Zimmi48/coq,SkySkimmer/coq,coq/coq,JasonGross/coq,SkySkimmer/coq,coq/coq,gares/coq