Redo 95bbb99 in a more correct manner.

1) Do not increment the frame rate returned by SDL by 1. Incrementing
   is unnessecary, more or less up to date versions on Nvidias, AMDs
   and Intels GPU driver on relevant platform return an value that's
   either correct or rounded up to next integer. And SDL itself also
   rounds up to the next integer. At least in current versions. In fact,
   incrementing the value by one is harmfull, it messes our internal
   timing up and leads to subtile miss predictions. Working around that
   in frame.c would add another bunch of fragile magic... So just do
   it correctly. If someone still has broken GPU drivers or SDL versions
   that are rounding down the could set vid_displayrefreshrate.
2) The calculation of the 5% security margin to pfps in frame.c was
   wrong. It didn't take into account that rfps can be slightly wrong
   in the first place, e.g. 60 on an 59.95hz display. Correct it by
   comparing against rfps including the margin and not the plain value.

src/client/vid/glimp_sdl.c

@@ -401,12 +401,5 @@ GLimp_GetRefreshRate(void)
 		}
 	}
 
-	/* The value reported by SDL may be one frame too low, for example
-	   on my old Radeon R7 360 the driver returns 59hz for my 59.95hz
-	   display. And Quake II isn't that accurate, we loose a little bit
-	   here and there. Since it doesn't really hurt if we're running a
-	   litte bit too fast just return one frame more than we really have. */
-	glimp_refreshRate++;
-
 	return glimp_refreshRate;
 }

src/common/frame.c

@@ -525,8 +525,7 @@ Qcommon_Frame(int msec)
 	   scene may be more complex than the previous one and SDL
 	   may give us a 1 or 2 frames too low display refresh rate.
 	   Add a security magin of 5%, e.g. 60fps * 0.95 = 57fps. */
-	pfps = (cl_maxfps->value > rfps) ? floor(rfps * 0.95) : cl_maxfps->value;
-
+	pfps = (cl_maxfps->value > (rfps * 0.95)) ? floor(rfps * 0.95) : cl_maxfps->value;
 
 	/* Calculate average time spend to process a render
 	   frame. This is highly depended on the GPU and the

src/game/g_monster.c

@@ -262,7 +262,9 @@ M_CheckGround(edict_t *ent)
 		VectorCopy(trace.endpos, ent->s.origin);
 		ent->groundentity = trace.ent;
 		ent->groundentity_linkcount = trace.ent->linkcount;
-		ent->velocity[2] = trace.ent->velocity[2];
+
+		// FIXME
+		ent->velocity[2] = 0;
 	}
 }