Castero

**Fixed**
* Fixed some files not being properly linked on install.

**Added**
* The client now uses an sqlite database file for storing data (sqlite added as
a dependency).
* Added support for marking episodes as played.
* Added a metadata-less perspective (SimplePerspective) accessed with `3`.

**Changed**
* Menus are now able to update dynamically from the database.

**Deprecated**
* The old JSON `feeds` file is no longer used, in favor of a `castero.db` file
in the same location. The client will migrate your `feeds` file to the new
database upon starting if necessary. There are no known issues with this
process, but your original file is not modified regardless (please create an
Issue if you have any problems!).

**Fixed**
* Fixed a crash when trying to view the metadata of 0 episodes.

**Added**
* Added a separate config option for seeking forwards/backwards - Thanks
mtostenson!

**Changed**
* FeedErrors will give more descriptive information in the status bar.

**Fixed**
* Fixed a potential crash when trying to run without libmpv.
* Fixed a crash when an unused player library is uninstalled.
* Fixed an issue where some websites would block the client since it did not
send requests with a user agent.

**Added**
* Added support for extracting plaintext from HTML metadata descriptions (can
be disabled in config).
* Added an option for right-aligning episode time/duration.
* Added an option to limit the number of episodes in a feed.
* Added an option to disable the default status message.
* Added perspective keys to help menu.

**Fixed**
* mpv support now uses the python-mpv library instead of pympv, which may fix
installation problems for some users.
* Fixed an issue where client could crash when adding episodes to queue while
using mpv.
* Fixed a crash when trying to determine whether mpv/libmpv was available.
* Fixed a crash when trying to delete nothing on queuelisting perspective.
* Fixed a crash when going to episodes menu for a feed with no episodes.
* Fixed incomplete metadata being displayed when viewing a feed with a single
episode.

**Added**
* Added support for playback with mpv as an alternative to VLC.
* Added foundational support for displaying metadata in menus (i.e. download
status) - Thanks nbastin!
* Added support for background transparency (if available on your terminal
emulator) - Thanks aneum7!
* Added an option for disabling vertical bars/borders between menus.

**Fixed**
* Fixed an issue where the client would attempt to download remote media while
offline - Thanks nbastin!
* Fixed an issue where the client would sometimes break your config while
trying to migrate items with blank values.
* Prevented crashing on some download errors; instead, a status/error message
is displayed - Thanks nbastin!
* Improved wrapping support for CJK text - Thanks Rand01ph!
* Updated Requests version in response to CVE-2018-18074.

**Fixed**
* Fixed an issue where config files would not properly migrate when a new
config section was added.