configmanager, hostmanager, prosody: Almost complete removal of section-related code, and the infamous 'core' section. Still backwards-compatible with API users.
prosody: Add COMPAT note about globals
util.pposix: Allow fetching RLIMIT_NICE when available
hostmanager: Use prosody.hosts instead of 'hosts' global
hostmanager: Use rawget to check for activated hosts to prevent recursion in dynamic host loaders
s2smanager, mod_s2s, mod_dialback, mod_saslauth: Move s2smanager.make_authenticated() to mod_s2s, and plugins now signal authentication via the s2s-authenticated event
mod_s2s: Add controls for certificate validation via the s2s_secure_auth option. Plugins can now return false from handling s2s-check-certificate to prevent connection establishment (s2sin+s2sout)
Merge 0.9->trunk