optimized seed_rng

optimized string_generator
fixed compile bug in string_generator for OS X

[SVN r58653]

libs/uuid

@@ -1 +1 @@
-Subproject commit 2f3f75827e2de3fce2f9f3f7172232159488022e
+Subproject commit 8807fd1e6c3af697bd88ea1a95f9d47cc060eb11