Move std::map initialization outside of draw_rr_edges() to avoid redundant reinitialization.

[soheilshahrouz]

This made graphics more responsive when edges are drawn.

[AlexandreSinger]

LGTM, but I just had one comment about the name of the map.

TBH, if this does make a noticeable difference, we should really consider not using a map for this lookup. This is showing that the compiler is actually creating the map object and we are looking up into that map at runtime. Maps are pretty slow when we are doing a lookup like this. We should really be using a simple helper function. This will likely make the lookup much cheaper.

We can ignore my above comment, since your change only makes the code better, but we should prevent code like this in the future in my opinion.

[amin1377]

Looks good, Soheil! Thanks!