[Image-SIG] Correct raw mode for 16-bit .bmp files

[Alexey Borzenkov]

Hi everyone,

Today I stumbled upon a 16-bit .bmp file that when opened with PIL had
very-very wrong colors. While looking for the cause I finally read
MSDN documentation on BITMAPINFOHEADER, where it says that by default
(i.e. when BI_BITFIELDS is not specified in biCompression field)
16-bit bitmaps have 5-bits for each color band, thus in
BmpImagePlugin.py it should be:

-    16: ("RGB", "BGR;16"),
+    16: ("RGB", "BGR;15"),

I wonder if there's any collision with OS/2 16-bit bitmaps though?
(don't even know where to start looking for information on them) If
not it would be good if it could be fixed on trunk.

Thanks,
Alexey.