for the floating-point engine, switch from "modulus" to word_size to

be able to handle 48 bits on all platforms (usually the mantissa of a
double)


[SVN r15658]

libs/random

@@ -1 +1 @@
-Subproject commit 63825754bebf4eaa9bba07e1260cbfc31f5d2315
+Subproject commit 89b028375ba6f229d5889cc32017fb1b3df6c7e4