Speed up Acl.fromReader

It should run 9x faster than before now.

Past mistakes:

* InetAddress.parseNumericAddress throws TWO exceptions underthehood if the string passed is invalid. This caused a huge overhead;
* CharSequence.split in Kotlin is EXTREMELY SLOW.

mobile/src/main/java/com/github/shadowsocks/utils/Subnet.kt

@@ -25,15 +25,15 @@ import java.util.*
 
 class Subnet(val address: InetAddress, val prefixSize: Int) : Comparable<Subnet> {
     companion object {
-        @Throws(IllegalArgumentException::class)
-        fun fromString(value: String): Subnet {
-            val parts = value.split('/')
-            val addr = parts[0].parseNumericAddress()
-            return when (parts.size) {
-                1 -> Subnet(addr, addr.address.size shl 3)
-                2 -> Subnet(addr, parts[1].toInt())
-                else -> throw IllegalArgumentException()
-            }
+        fun fromString(value: String): Subnet? {
+            @Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
+            val parts = (value as java.lang.String).split("/", 2)
+            val addr = parts[0].parseNumericAddress() ?: return null
+            return if (parts.size == 2) try {
+                Subnet(addr, parts[1].toInt())
+            } catch (_: NumberFormatException) {
+                null
+            } else Subnet(addr, addr.address.size shl 3)
         }
     }
 

mobile/src/main/java/com/github/shadowsocks/utils/Utils.kt

@@ -11,31 +11,20 @@ import android.support.v4.app.FragmentManager
 import android.support.v7.util.SortedList
 import android.util.TypedValue
 import com.github.shadowsocks.App.Companion.app
+import com.github.shadowsocks.JniHelper
 import java.lang.reflect.InvocationTargetException
+import java.net.Inet4Address
 import java.net.InetAddress
 import java.net.URLConnection
 
-private val isNumericMethod by lazy { InetAddress::class.java.getMethod("isNumeric", String::class.java) }
-private val parseNumericAddressMethod by lazy {
-    try {
-        InetAddress::class.java.getMethod("parseNumericAddress", String::class.java)
-    } catch (_: NoSuchMethodException) {
-        null
-    }
-}
 private val fieldChildFragmentManager by lazy {
     val field = Fragment::class.java.getDeclaredField("mChildFragmentManager")
     field.isAccessible = true
     field
 }
 
-fun String.isNumericAddress(): Boolean = isNumericMethod.invoke(null, this) as Boolean
-fun String.parseNumericAddress(): InetAddress =
-        if (parseNumericAddressMethod == null) InetAddress.getByName(this) else try {
-            parseNumericAddressMethod!!.invoke(null, this) as InetAddress
-        } catch (exc: InvocationTargetException) {
-            throw exc.cause ?: exc
-        }
+fun String.isNumericAddress() = parseNumericAddress() != null
+fun String.parseNumericAddress() = JniHelper.parseNumericAddress(this)
 
 fun parsePort(str: String?, default: Int, min: Int = 1025): Int {
     val x = str?.toIntOrNull() ?: default