v0.2

• New plugin system based on Doug Hellmann's stevedore package, allows packages to extend spreads without being included in the core distribution
• The driver for CHDK cameras no longer relies on gphoto2 and ptpcam, but relies on Abel Deuring's pyptpchdk package to communicate with the cameras.
• Wand is now used to deal with image data instead of Pillow
• New 'colorcorrection' plugin allows users to automatically correct white balance.
• Improved tutorial