m_modules: make modreload work like restart

m_modules: make modreload work like restart

/modrestart used to be implemented as a normal command and could crash
when used remotely because it would reload m_encap, which was on the
call stack at the time. This was fixed in 41390bfe5f. However,
/modreload has exactly the same problem, so I'm giving it the
same treatment.

Incidentally: This bug was first discovered in ircd-seven, where the
`/mod*` commands themselves live in the core, so m_encap was the only way
the crash could happen (and it didn't most of the time, because m_encap
would only be moved if you got unlucky). But `/mod*` are in modules in
charybdis, so /modrestart would have unloaded the code it was in the
middle of executing. With that in mind, I'm not sure how it ever
appeared to work.