Generalized support for referencing resources in external WIMs
In preparation for supporting "delta" WIMs, this commit generalizes the library
interface for handling split WIMs.
Instead of cluttering up various functions with additional split WIM parameters,
there is now a function wimlib_reference_resource_files() available that can
load additional resources (e.g. from a split WIM part) into a WIMStruct that has
metadata available (e.g. the first part of a split WIM, or a standalone WIM).
wimlib_reference_resource_files() can handle file globbing by itself, so it
actually makes it easier for library users to process split WIMs.
Lower-level APIs wimlib_reference_resources() and wimlib_unreference_resources()
are also provided, but not yet used directly by `wimlib-imagex'.
Some instances of WIMLIB_ERR_SPLIT_UNSUPPORTED error returns were changed to
the new error code WIMLIB_ERR_METADATA_NOT_FOUND.
This commit also re-writes wimlib_export_image() to correctly roll back changes
on multi-image exports and better handle resources in the source WIM being
missing, as well as add a flag to make all destination image(s) unnamed.
git://wimlib.net / wimlib / commit