Improve Joystick Support (#43)

* improve joystick configuration searching; now supports alternative names for the same controller

* add configurations for multiple controllers i had lying around

* improve readability of code that checks for a key in a JSON object by using .contains() instead of .find() == .end()

* version bump to 0.2.5

Fix AppImage Packaging

- The new version of cudnn loads component .so files very late, so AppImage cannot automatically detect that they are needed. Fix this by explicitly including them.

Recreate release tag.

Merge pull request #33 from markleybros/vidcap-unblocking

Video Capture Unblocking & Gamepad Support

Video Output Support (#31)

Introduces the following:

- YerFace can now multiplex input streams and save them to an output video file. This completes the loop on a very important studio workflow.
- Logging system has been completely rewritten, providing:
  - Colorization at the console.
  - Adjustable verbosity.
  - Optional logging to a file.
  - Consistent formatting of all log events, including log events from third party libraries.
  - Millisecond precision timestamps.
- Massive improvements to documentation.
- Various bugfixes.
- Version bumped to 0.2.0.


Commit List:

* Introduces Video Output support; many bugfixes.

* fix some warnings that clang discovered for us

* introduce WIN32 support for this branch

* some minor corrections in multiplatform code

* avoid a deadlock during emergency shutdown

* correct some more bad deadlock-on-emergency-stop bugs

* improve logger performance on windows

* introduce a deadlock timer in the mutex lock macro

* improve libav* logging (re-add class context tags that have been missing since logging got redone)

* introduce a macro to try deleting an object, but catching if the destructor throws; persist through the shutdown sequence even if a destructor throws; mark all destructors as potentially being able to throw

* trying to track down a memory corruption issue

* improve build script to allow for either debug or release builds

* more troubleshooting of mutex issues

* clean up the code a bit

* work around MSVC limitations around constexpr