Fix compile warnings as seen on g++ 4.4.7
Fix module loading in PURE_STATIC builds
Remove ModuleManager::ModCount and GetCount()
Deduplicate code in modmanager_static and modmanager_dynamic
Automatically register ServiceProviders created by modules
Remove InspIRCd::HandleRehash functor

Call InspIRCd::Rehash() from cmd_rehash and from the SIGHUP handler
Hide all symbols that aren't exported explicitly

In addition to reducing the sizes of all binaries this also helps the optimizer
Change allocation of a few services to make use of auto registration