Improve floating point number formatting

src/main/kotlin/moe/nea/firmament/util/FirmFormatters.kt

@@ -0,0 +1,15 @@
+package moe.nea.firmament.util
+
+import com.google.common.math.IntMath.pow
+import kotlin.math.absoluteValue
+
+object FirmFormatters {
+    fun toString(double: Double, fractionalDigits: Int): String {
+        val long = double.toLong()
+        val δ = (double - long).absoluteValue
+        val μ = pow(10, fractionalDigits)
+        val digits = (μ * δ).toInt().toString().padStart(fractionalDigits, '0').trimEnd('0')
+        return long.toString() + (if (digits.isEmpty()) "" else ".$digits")
+    }
+
+}