Only read /dev/random once when the program starts

rather than for every connection, to "conserve entropy".

--HG--
extra : convert_revision : 21df240b71c0af8454725dec9abb428dd4bb97a2

random.h

@@ -28,6 +28,7 @@
 struct mp_int;
 
 void seedrandom();
+void reseedrandom();
 void genrandom(unsigned char* buf, int len);
 void addrandom(unsigned char* buf, int len);
 void gen_random_mpint(mp_int *max, mp_int *rand);