Fix things that framerate unlock will expose

Hoikas pointed these out to me
https://github.com/H-uru/Plasma/pull/503
https://github.com/H-uru/Plasma/pull/505

Sources/Plasma/PubUtilLib/plInterp/hsInterp.cpp

@@ -404,7 +404,7 @@ void hsInterp::GetBoundaryKeyFrames(hsScalar time, UInt32 numKeys, void *keys, U
 {
 	hsAssert(numKeys>1, "Must have more than 1 keyframe");
 	int k1, k2;
-	UInt16 frame = (UInt16)(time * MAX_FRAMES_PER_SEC);
+	float frame = (time * MAX_FRAMES_PER_SEC);
 
 	// boundary case, past end
 	if (frame > GetKey(numKeys-1, keys, size)->fFrame)

Sources/Plasma/PubUtilLib/plInterp/plAnimTimeConvert.cpp

@@ -557,11 +557,16 @@ hsScalar plAnimTimeConvert::WorldToAnimTime(double wSecs)
 			{
 				if (secs > fLoopEnd)
 				{
-					secs = fmodf(secs - fLoopBegin, fLoopEnd - fLoopBegin) + fLoopBegin;
+					float result = fmodf(secs - fLoopBegin, fLoopEnd - fLoopBegin) + fLoopBegin;
+					// if fLoopBegin == fLoopEnd == 0, result will not be a number
+					if (!isnan(result))
+					{
+						secs = result;
 						wrapped = true;
 					}
 				}
 			}	
+		}
 		else
 		{
 			if (IGetLatestState()->fStartAnimTime < fLoopBegin)
@@ -576,11 +581,16 @@ hsScalar plAnimTimeConvert::WorldToAnimTime(double wSecs)
 			{
 				if (secs < fLoopBegin)
 				{
-					secs = fLoopEnd - fmodf(fLoopEnd - secs, fLoopEnd - fLoopBegin);
+					float result  = fLoopEnd - fmodf(fLoopEnd - secs, fLoopEnd - fLoopBegin);
+					// if fLoopBegin == fLoopEnd == 0, result will not be a number
+					if (!isnan(result))
+					{
+						secs = result;
 						wrapped = true;
 					}
 				}
 			}				
+		}		
 
 		if (fFlags & kWrap)
 		{