Display all parts of message prefix in notification

Previously, we only got the first part -- which would be "@" for an op, and not their nick.
Improve plugin regular expressions, load imgur over https if enabled
Update logo

Shading and legibility, slightly less creepiness.
Merge pull request #217 from lorenzhs/notificationfix

Display all parts of message prefix in notification
Merge pull request #218 from lorenzhs/pluginregex

Improve plugin regular expressions, load imgur over https if enabled
Merge pull request #219 from acous/update-logo

Update logo
Add SVG
Merge pull request #220 from acous/update-logo

Add SVG logo
Add a isNicklistEmpty method to buffer model, speed up nicklist decision

Flattening the nicklist is really unnecessary. This method is 10x faster for short
nicklists, and much faster for buffers with lots of users.
Defer nicklist loading until buffer is opened

Drastically improves startup time for users with buffers that have thousands of users
Remove debug logging
Load lines before nicklist

Nicklist is not nearly as important as the actual lines, load them first for better perceived performance. Parsing the nicklist can take a noticeable amount of time for channels with thousands of occupants.

This also improves/fixes the nicklist emptiness check
Fetch nicklist by buffer name, not pointer

An invalid pointer will crash WeeChat, while an invalid name will not. A pointer
becomes invalid e.g. if the buffer is closed by another client, g-b not updated,
and the buffer then selected in g-b.
Merge pull request #226 from lorenzhs/removelog

Remove debug logging
Merge pull request #225 from lorenzhs/defernicklist

Defer nicklist loading until buffer is opened
Try to fetch all unread lines if that is a reasonable amount

Partially fixes #139 in that it tries to accomplish this, but until we can request
only non-filtered lines from WeeChat, the best thing we can do is guessing.
Merge pull request #224 from lorenzhs/fetchall

Try to fetch all unread lines if that is a reasonable amount
Bigger logo on landing page

I rendered the svg with inkscape
Merge pull request #227 from lorenzhs/titlepage

Bigger logo on landing page