slicer/slice.c (eq): increase epsilon from 1e-6 to 1e-5

The lower value incorrectly tripped a verticality test.

slicer/slice.c

@@ -69,7 +69,7 @@ static void bbox(float x, float y)
 
 static inline bool eq(float a, float b)
 {
-	return fabsf(a - b) < 1e-6;
+	return fabsf(a - b) < 1e-5;
 }