Castero

**Added**
* Automatically migrate users' config file when the client updates and adds or
removes a new config option.
* The client will now properly resize when the size of the terminal changes.

**Changed**
* Metadata window will now properly extend to the right edge of the terminal.

**Fixed**
* Fixed an issue where the queue would not properly recognize that the current
episode had finished.
* Fixed footer text not being truncated, which caused errors if the screen size
was too small.

**Added**
* Added support for downloading episodes for offline playback.

**Fixed**
* Fixed the description of some fields in the default config file.
* Fixed an issue where the client would not properly obey the reload_on_start
config option.
* Fixed an issue where pressing enter or space with no feeds would crash the
client.

**Added**
* Added config options for client colors.
* Added config option to automatically reload feeds on startup.
* Handle -h or --help flag to display help text instead of starting the client.

**Added**
* You can now add entire feeds to the queue.
* Running the client with too small a screen (minimum arbitrarily defined at 20
cols and 8 lines) will now raise an error.

**Changed**
* Reloading feeds now runs on a separate thread to allow the user to continue
interacting with the client.
* Refactored setup.py with additional args in preparation for PyPi upload.

**Fixed**
* Fixed an issue where reloading feeds caused the user's selection to remain in
the episodes menu, resulting in strange behavior.
* Fixed an issue where status messages would overlap with each other after
being replaced.

**Added**
* Pressing 'r' will now reload/refresh your feeds list.
* Added support for showing status messages in the footer, and certain commands
will now display status messages after running (or if an error occurs).

**Fixed**
* Fixed an issue where recreating menus often caused them to be smaller than
normal.
* Fixed an issue where a feeds file with duplicate keys would not load.