GetChartsMatchingFilter: hacky rate addition & limit charts out to 1 each

this addition is really bad, should find a more consistent solution further down the line

Author: poco0317

src/Etterna/Models/Songs/Song.cpp

@@ -1651,8 +1651,15 @@ Song::GetChartsMatchingFilter() const
 			 currate -= 0.1F) { /* Iterate over all possible rates.
 								 * The .01f delta is because floating points
 								 * don't like exact equivalency*/
-			if (i->MatchesFilter(currate))
+			// we must add 0.001 to the currate to force it to align when
+			// converting the rate to an index within GetMSD
+			// TODO: less hacky solution for this (this isnt the only place we do this)
+			if (i->MatchesFilter(currate + 0.001F)) {
+				// chart matched on a rate, add it only once
 				matches.push_back(i);
+				break;
+			}
+			
 		}
 	}
 	return matches;