Fix hood-publicizing bug

D'oh! Looks like we only provided the fifty first modified public hoods to the nexus. Let's try doing the fifty most recently modified hoods instead...
Fix Gira Baskets

Heh, so, for plSynchedObject SDL updates, we were saving the update directly to the database instead of saving the merged blobs. This didn't work because the client only sends DIRTY fields in its updates. So, if the last basket update we get is an angular/velocity change with no position/orientation change, we've unset those fields in the DB. So, on subsequent link ins, they're at the DEFAULT, which is the origin (0, 0, 0). Winning!
Merge pull request #86 from Hoikas/sdl-fixes

Fix Gira Baskets
GCC 4.8 seems to require -pthread for the POSIX semaphore library
Fix const-correctness in stream writers
Fix const-correctness for some DS::String methods too
Merge pull request #87 from zrax/const_correct_write

Const correct writes
Merge remote-tracking branch 'huru/master'