Chandere

** Major rewrite of program in an attempt to make it more modular and easily extensible. **
* Rename to "Chandere."
* The "2" was appended in an attempt to keep this repository separate from an
older, synchronous version of the software, but that repository has since
been removed from Github.
* The codebase has been completely rewritten, and now operates on a system of
modularized website scrapers and actions. Adding support for a new website or
task no longer requires fiddling with fragile "contexts.
* The following features have been temporarily removed:
* Archiving posts to plaintext, SQL.
* Post filtering.
* Hammering the servers with --continuous
* Support for the following websites has been temporarily removed on a provisional basis:
* 76chan
* endchan
* lainchan
* nextchan
* uboachan

* No major changes, just a new stable release with some fixes for new aiohttp.

* Added support for Uboachan.
* Implemented handling for when the network is down or the imageboard is unreachable.
* Database archives now have a separate table for each board.
* Fixed several issues with continuous mode.
* Tracebacks are no longer shown when a user issues a signal interrupt.

* Very minor bugfix for the changed 8chan API.

* Fixed issues with image downloading on 8chan and Nextchan.
* Fixed issue regarding archiving to plaintext for Endchan and Nextchan.

* Added support for 76chan, Endchan and Nextchan.