Add WMath random functions

Fixes #34

cores/rp2040/WMath.cpp

+/*
+  Copyright (c) 2014 Arduino.  All right reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the GNU Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+extern "C" {
+  #include "stdlib.h"
+  #include "stdint.h"
+}
+
+void randomSeed( uint32_t dwSeed )
+{
+  if ( dwSeed != 0 )
+  {
+    srand( dwSeed ) ;
+  }
+}
+
+long random( long howbig )
+{
+  if ( howbig == 0 )
+  {
+    return 0 ;
+  }
+
+  return rand() % howbig;
+}
+
+long random( long howsmall, long howbig )
+{
+  if (howsmall >= howbig)
+  {
+    return howsmall;
+  }
+
+  long diff = howbig - howsmall;
+
+  return random(diff) + howsmall;
+}