load random.sfmt by default, and use it as default random-generator if sse2 is present

basis/random/backend/authors.txt

@@ -0,0 +1 @@
+Doug Coleman

basis/random/backend/backend.factor

@@ -0,0 +1,10 @@
+! Copyright (C) 2009 Doug Coleman.
+! See http://factorcode.org/license.txt for BSD license.
+USING: cpu.x86.features init kernel namespaces random
+random.mersenne-twister random.sfmt ;
+IN: random.backend
+
+[
+    sse2? [ default-sfmt ] [ default-mersenne-twister ] if
+    random-generator set-global
+] "bootstrap.random" add-init-hook

basis/random/mersenne-twister/mersenne-twister.factor

@@ -76,7 +76,3 @@ M: mersenne-twister random-32* ( mt -- r )
 : default-mersenne-twister ( -- mersenne-twister )
     [ 32 random-bits ] with-system-random
     <mersenne-twister> ;
-
-[
-    default-mersenne-twister random-generator set-global
-] "bootstrap.random" add-init-hook

basis/random/random.factor

@@ -112,4 +112,4 @@ PRIVATE>
     { [ os unix? ] [ "random.unix" require ] }
 } cond
 
-"random.mersenne-twister" require
+"random.backend" require

basis/random/sfmt/sfmt.factor

@@ -152,3 +152,6 @@ M: sfmt seed-random ( sfmt seed -- sfmt )
     uint-4{ HEX: dfffffef HEX: ddfecb7f HEX: bffaffff HEX: bffffff6 }
     uint-4{ HEX: 1 HEX: 0 HEX: 0 HEX: 13c9e684 }
     <sfmt> ; inline
+
+: default-sfmt ( -- sfmt )
+    [ random-32 ] with-secure-random <sfmt-19937> ;