Implement change-email, email-verification, account-recovery, and welcome notifications

Added netcup domains to global domains

Add an option to fetch and parse href="data:image"

Some sites are using base64 encoded inline images for favicons.
This will try to match those with some sane checks and return that.
These icons will have lower prio then the icons with a normal URL.

Update dependencies and toolchain
Update included equivalent domains with upstream changes

Add the ability to disable signups, but allow signups from a whitelist

This feature can be enabled by setting SIGNUPS_ALLOWED=false and
providing a comma-separated list of whitelisted domains in
SIGNUPS_DOMAINS_WHITELIST.

Fixes #727

Added tv.apple.com to global domains

cleaner startup exec in order to build the image and run the containe…

Add vim modeline for GitHub Linguist

Fixed issue/request #705

Added a config option to disable time drifted totp codes.
Default is false, since this is what the RFC recommends.

Added configurable smtp timeout.

 - Added config option for smtp timeout
 - Lowered default timeout to 15 seconds instead of default 60.

Updated some dependencies and used a git patch for lettre addressing
timeouts.

Fixed issue #709 creating icon_cache directory.

Now creates icon cache directory at startup.
And it also creates the directory if it went missing during runtime.
Also modified the icon_save/mark_negcache to be one.

When the icon_cache directory doesn't exists yet, and the first icon
catched is a miss this .miss file was not able to be created since the
directory was only created during a valid icon download.

Don't install mysql libraries for sqlite builds

Don't include excluded global equivalent domains during sync

Fixes #681

Trying to fix issue #687

- Using an older commit from rocket repo

Stop leaking usernames when SIGNUPS_ALLOWED=false