Define snprintf as _snprintf when under the influence of _MSC_VER.
Define int32_t and friends as __int32 and friends when under the influence of _MSC_VER.
Make include of unistd.h conditional on HAVE_UNISTD_H.
Propagate the unsigned char* change down the stack.
Add cast since XImage uses char* rather than unsigned char*.
Fix memory leak of image data.
Switch to use cairo_surface_write_png rather than a custom write_png_argb32.
Add test to exercise the cairo_image_surface_create_for_png function.
Add new testsvg script and accompanying imagediff program, (for interim SVG-based test suites while we wait for the standard cairo test suite to mature).
Split buffer_diff out into its own file for the purpose of imagediff.