Pyxel

- Updated the instruction of installation on Linux
- Fixed a warning in setup.py

- Added issue templates
- Added the description of issue templates in the manuals
- Fixed the clipping bug of drawing primitives

- Fixed the crush bug when entering the fullscreen mode
- Updated the description for Linux in the manuals
- Reverted to check the version number of glfw strictly
- Increased the sound buffer size
- Fixed the range of the sound picker in the sound editor

- Enabled to open a resource file by drop in Pyxel Editor
- Renamed the constants for the mouse buttons
- Added gamepad support
- Changed gamepad available for Example 2
- Fixed the crash bug when the window is minimized
- Modified the code of Example 6
- Added the refimg property to the Tilemap class
- Removed the img argument from the bltm API
- Updated the screenshot of Example 3

- Enabled to import png by drop in the image editor
- Fixed the crash bug caused by unsupported keys
- Enabled to play the piano with mouse in the sound editor
- Enabled to repeat undo/redo shortcuts

- Fixed the color pick bug of the image editor
- Changed the focus UI of the image editor