Small improvement to the pi approximation (#1292)

app/src/main/java/com/geeksville/mesh/util/LocationUtils.kt

@@ -14,6 +14,7 @@ import kotlin.math.cos
 import kotlin.math.log2
 import kotlin.math.pow
 import kotlin.math.sin
+import kotlin.math.PI
 
 /*******************************************************************************
  * Revive some of my old Gaggle source code...
@@ -181,7 +182,7 @@ fun latLongToMeter(
     lat_b: Double,
     lng_b: Double
 ): Double {
-    val pk = (180 / 3.14169)
+    val pk = (180 / PI)
     val a1 = lat_a / pk
     val a2 = lng_a / pk
     val b1 = lat_b / pk