[Image-SIG] PIL cannot read RGBA tiffs with no ExtraSamples tag

[Michael Babcock]

Maya 2012 writes these kind of tiff files. There is an alpha channel, 
but no ExtraSamples tag. Tracing the code, I believe adding a line such as

(II, 2, 1, 1, (8,8,8,8), ()): ("RGBA", "RGBa"),

to the OPEN_INFO dictionary in TiffImagePlugin.py would fix this. I'm 
only guessing at the "1" default value for ExtraSamples because that's 
what Maya used to add in older versions.