Allow protected or owners to register channels too

In Unreal and InspIRCd, the protected and owner channel status also
confer operator status.  Allow these statuses to register channels as
well.  As only protocols that have these statuses set the status flags
in the chanuser objects, this is safe for any protocol module.

Fixes #188
linker: Avoid leaving the error string uninitialized.

Note that libmowgli-2 already calls dlerror(), so it cannot be called again.
Put in a generic error message.
nickserv/drop: Fix format string in confirmation message.
chanserv/register: Fix silly bug that allowed nonchanops to register channels.
libathemecore, *serv: unify all three copies of create_challenge()

Should've done this earlier, I guess.
Merge pull request #200 from grawity/unify-create-challenge

libathemecore, *serv: unify all three copies of create_challenge()
Add createburst to .gitignore
Update contrib modules snapshot
Update contrib modules snapshot again
Merge branch 'master' of github.com:atheme/atheme
Update contrib modules snapshot one last time