Code in core source file which depend upon ID-WSF symbols have been
conditionalized, and each id-wsf source file now include directly its
need string header.
* lots of files: Explicitely set all field of initialized structures,
in order to remove -Wno-missing-field-initilizers from needed
compiler options when using -Wall -Wextra.
- remove unused parameter from private function signatures
- remove unused variable
- initialize variable potentially accessed uninitialized
- add G_GNUC_UNUSED if function is public or adhering to an interface, and a
parameter is unused.
- if ID-WSF is not compiled in, define stubs with G_GNUC_UNUSED on parameters.
The goal is to compile with -Werror.