Codplayer

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* New command: `ejected`. This is used by the `on_cd_eject.sh` script
to avoid `codplayerd` trying to eject an already ejected disc.

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Some significant and breaking changes merits bumping the major version
number. For this release the web control widget was moved to a
separate repository to let it have its own version numbering.

Breaking changes

To support the additional daemons (see below) and simplifying the code
in general, codplayer is now fully dependent on ZeroMQ for all
intra-component communication. This led to changes in the
configuration file structure to make configuration of the
all-important ZeroMQ endpoints easy.

The old state publishing and command factory classes used in
`codplayer.conf` has been removed. In its place are ZeroMQ channel
definitions in `codmq.conf`.

`codctl` now reads `codmq.conf`, instead of `codplayer.conf`.

`codplayer.conf` has changed format, removing the state and command
factory lists and instead just having a new parameter referencing the
`codmq.conf` file.

The old FIFO command interface and the state files have been removed,
on the assumption that the ZeroMQ interface is much more useful. If
these old interfaces are needed, they could be reimplemented as
components using the the ZeroMQ API.

`codrestd` is now a daemon and behaves in the same way as all the
other codplayer daemons. Thus `codrest.conf` have additional required
configuration properties: `pid_file` and `log_file`.


Hardware support

An IO control board, connected to a Raspberry Pi GPIO port, is now
supported (and described in the `doc` directory). This board has two
corresponding daemons:

* `codlircd`: read remote control events from `lircd` and send
keypress ZeroMQ events

* `codlcd`: Display player status on an LCD and status LED


Daemon plugins

The various daemons can have plugins, listed in the config files.

This release adds one such plugin for `codplayerd`:

* `codplayer.remotecontrol.RemoteControl`: consumes keypress events
and translates them into commands.


Other fixes

* All daemons support new config parameter `initgroups`. If set to
`True` and the daemons are started with root and then drops
privileges, they will acquire all the groups the daemon user
belongs to, and not just the one specified in the config.

* codctl: new flag -q/--quiet to suppress output from action commands.

* https://github.com/petli/codplayer/issues/37: handle multiple error
alerts in the database admin web UI.

* Eject discs in background process to avoid hanging the IO loop
while the hardware spits out the disc.

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New features

Discs can be linked as an alias for another disc. An example usecase
is to play a remastered CD when inserting the original release.

If a linked disc is played, the source disc ID is available in the
`state.State.source_disc_id` parameter.


Other fixes

* https://github.com/petli/codplayer/issues/31: data file was stored
as an absolute path.

* https://github.com/petli/codplayer/issues/32: error handling broken
when disc can't be read.

* https://github.com/petli/codplayer/issues/33: highlighting broken
when discs have skipped tracks.

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The ripping process has been completely refactored. The old process
used cdrdao to rip both audio and the full TOC in a single pass. This
had a bunch of problems:

* cdrdao isn't as good as cdparanoia to handle damaged discs,
resulting in some skips and crackles on those

* the error-correcting code in cdrdao introduces a lot of errors in
the subchannel reading that the TOC depends on, so pregaps and
indices on tracks are generally way off

* it just gets confused by discs with hidden tracks before the first
proper track

This refactoring solves this, by splitting the ripping process into
two phases: first get the audio with cdparanoia, then an undisturbed
TOC with cdrdao.

All discs in a pre-1.0 database will be reripped with the new process
after deploying codplayer 1.0, but the change is backward compatible
to retain any disc information and edits previously added. The result
is thus that discs are reripped to a higher quality, without having to
restart with a blank database.

Incompatible changes

Changes requiring action from the user:

* The configuration in `codplayer.conf` have new mandatory parameters:
`cdparanoia_command` and `FilePublisherFactory(rip_state_path =
...)`

* cdparanoia must be installed on the system


Good to know:

* Discs ripped with the old method that never had any information
added in the admin GUI (i.e. only had a `.toc`, not a `.cod`) are no
longer visible in the admin GUI. They will re-appear when reripped
with the new process.


Changes affecting codplayer clients:

* Ripping state is no longer part of `state.State`, but handled in a
separate `state.RipState` object instead. The ZeroMQ state updater
emits `rip_state` messages with these objects.

* `Track.number` may now be 0, indicating a "hidden" track before the
nominal first track.


Other fixes

General:

* All scripts now have a `--version` option
* The player command `version` returns the currently running daemon verson


Database admin GUI:

* User documentation
* Don't overwrite any existing track settings when fetching
disc information from Musicbrainz
* More efficient sorting speeds up page load


Web control widget:

* Timeout of 30 seconds after the last client disconnects before
stopping the state subscriptions


codplayerd:

* Limit rip spead with new (optional) config parameter
`cdrom_read_speed`

* Fix https://github.com/petli/codplayer/issues/30: handle errors on
pause/resume in `c_alsa_sink` correctly

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* Fixes https://github.com/petli/codplayer/issues/28: crashed on
errors before playing any packet at all, e.g. on missing USB audio
device.

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First fully packaged release.