Note that attachments will be lost. This is a TODO.

This allows registered plugins to execute code when loaded. This will
also allow the Lua support code to be a plugin.

Closes: https://todo.sr.ht/~sircmpwn/koushin/54

And mark original message as answered.

Closes: https://todo.sr.ht/~sircmpwn/koushin/15

Closes: https://todo.sr.ht/~sircmpwn/koushin/46

The timer channel may already have been drained by `case <-timer.C`. In
this case, we need not to drain it again or we'll block forever.

To fix this, stop draining the timer channel. Since we're not going to
use the timer again anyway, it should be fine.

Closes: https://todo.sr.ht/~sircmpwn/koushin/49

koushin now takes a list of upstream URLs instead of an IMAP and SMTP
URL. This allows to specify upstream server URLs for plugins. In the
future, this will allow for auto-discovering upstream servers based on a
single domain name.

References: https://todo.sr.ht/~sircmpwn/koushin/49

This is not 100% idiot-proof, but still makes it mroe difficult for
plugins to steal credentials.

There's no way around having a global mutex, because we need to update
the HTTP routes when reloading plugins. During reload we need to lock
the whole server.

Closes: https://todo.sr.ht/~sircmpwn/koushin/43

References: https://todo.sr.ht/~sircmpwn/koushin/43

This only reloads templates for now. In the future it'll also reload
Lua plugins.

This will be useful to implement hot reload.

Disallows loading external ressources. Providers can override it with
their reverse proxy settings.

Take a *Context instead of a echo.Context. This saves a type assertion
in each handler.

This allows to access the request metadata and the session from injectors.

This allows Go plugins to easily inject global data.