RenderData will be used for an interface.

References: https://todo.sr.ht/~sircmpwn/koushin/36

Maybe we should add a confirmation step in the future.

References: https://todo.sr.ht/~sircmpwn/koushin/36

References: https://todo.sr.ht/~sircmpwn/koushin/36

This is a public type other plugins and templates may want to access.

Closes: https://todo.sr.ht/~sircmpwn/koushin/13

Closes: https://todo.sr.ht/~sircmpwn/koushin/23

This gives more flexibility in Session for optimizations, e.g. keep the
SMTP connection around for some time if possible.

Now that all templates are provided by plugins, there's no need to have
a public/ directory. Themes can be in /themes instead of /public/themes.

This plugin offers base IMAP/SMTP functionality.

References: https://todo.sr.ht/~sircmpwn/koushin/39

References: https://todo.sr.ht/~sircmpwn/koushin/39

Fixes: f07ab52632 ("Add docs")

And unexport a few internal functions.

This isn't intended to be used by plugins.

I'm uneasy exposing the token to plugins, I prefer to hide it if
possible to prevent mis-use.

This change allows plugins to logout users.

This allows plugins to access it.

GlobalRenderData contains some global metadata that can be obtained from
any template.

RenderData is a base type for template data. It contains a Global field
with global metadata and an Extra field for plugins.

This is the first step to allow each user to have a different theme.

This function doesn't render anything, it just adds extra data to the
template data.

References: https://todo.sr.ht/~sircmpwn/koushin/6

The session manager has been upgraded to deal with reconnections.

Each session has its own expiration timer. Each time a request is
received, the expiration timer is reset.

A session can be closed (this is used when the user wants to logout).

When the IMAP connection is closed by the server, it's set to nil in the
session. The next time an IMAP command needs to be issued, the
connection is re-established.

Closes: https://todo.sr.ht/~sircmpwn/koushin/30

This will allow SessionManager to re-connect when the IMAP server logs
the user out.

This makes sure fields filled by vanilla koushin keep the right type. A
new Extra field allows plugins to attach their own data.

This also makes it easier to write Go plugins, which would have trouble
working with interface{}.