sane.ds: Add partial stub support for ICAP_PIXELTYPE, with tests. Fixes a first crash in Adobe Acrobat scanning support.

- Use HandleToLong to get to the user handle.
- Use GetWindowLongPtr to retrieve a pointer.

widl: Change write_type_def_or_decl and write_type_decl to take an argument name instead of a printf format.

Fixes failures in these tests on NT4.

The wireCLIPFORMAT represents the memory equivalent format of the wire
format and not the wire format itself.

Also update the tests to do the same.

Some programs alter propsheet style in the callback during creation to make
"embedded" propsheets. PSH_MODELESS controls modal/modeless operation only.