Fixed a bunch of missing includes and forward declares.  I was trying to benchmark with precompiled headers off, but we'll have to do a bunch more cleanup before it's possible to disable that feature cleanly.  Not reviewed.

Result of svn merge -r107256:107258 svn+ssh://svn/svn/user/phoenix/license_2009_merge into trunk. QAR-1165

dataserver-is-deprecated

Result of svn merge -r71162:71205 svn+ssh://svn/svn/linden/branches/new-license into release. only changes files which are not deployed or the comments section of code.