Poppler 0.8.1 released

Available from
http://poppler.freedesktop.org/poppler-0.8.1.tar.gz

Changes since 0.8.0:
core:
 * Do not call FT_Done_Face on a live cairo_font_face_t as it might cause crashes
 * Do not take into account Colorspace resource subdictionary for image XObjects
 * Downsample 16 bit per component images to 8 bit per component so they render

build system:
 * Link to pthread when the system needs it

windows:
 * Fix comparing against NULL instead against INVALID_HANDLE_VALUE when calling FindFirstFile

0.8.2 version is scheduled for May 26th

Testing, patches and bug reports welcome.