Pyglet

Improvements
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- Added new experimental `gui` module. Currently this only contains basic widgets.
- Added new `Group.visible` property, to toggle rendering of entire Groups when used in a Batch.
- Added `Sprite.paused` and `Sprite.frame_index` helper properties for controlling Animations.
- Reorganized the examples folder.
- Added new CenteredCamera example.
- Backport pyglet.math from 2.0, for more exposure and testing.
- Consolidate Codec logic into base class to reuse among various modules.

Bugfixes
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- Fix crash when no audio device is available.
- Prevent `__del__` spam in DirectSound buffers and Wave decoder.
- Explicitly cast warnings.warn message to a str to prevent numba error.

Bugfixes
--------
- Fix infinite recursion error on OSX. (5)
- The on_mouse_scroll event no longer clamps to int, preventing lost motion on trackpads.
- Prevent traceback when DirectSound buffers are garbage collected on exit.
- Fix StaticSource playback with WMF decoder (streaming=False).
- Fix colorspace for WMF video decoding.
- Prevent crash on garbage collection for FFmpeg decoder.

Improvements
------------
- New image decoder leveraging Windows Imaging Component (WIC).
- TextureAtlas/Bins now have a `border` argument for leaving n-pixels of blank space around
images when adding. By default the `resource` module leaves a 1-pixel space around images.
- Many small documentation fixes and corrections.

Bugfixes
--------
- GStreamer decoder clamped to 16bit sample width, since the default OpenAL backend on Linux does
not support anything higher.

Improvements
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- shapes module: added `Circle.rotation` property and blending to standalone shape `draw` methods.
- shapes module: added missing `delete` and `__del__` methods.
- The ImageMouseCursor has a new `accelerated` parameter to allow custom mouse points to be drawn
natively on Windows and Linux.

Bugfixes
--------
- Avoid WMFDecoder crash when mixing pyglet with other tookits. (174)
- Prevent EventDispatcher subclasses from hiding AttributeError exceptions.

Improvements
------------
- Added `pyglet.shapes` module for creating simple 2D shapes.

Bugfixes
--------
- Fix memory leak caused by not freeing stale buffers and textures.