Unify error codes engaged in import/export
Before this patch, there were two layers of error codes:
KisImageBuilder_Result in KisImageBuilderResult.h
later converted into ConversionStatus in KisImportExportFilter.h
In case of usage of libraw, there were also libraw error codes.
After this patch, only one error code system and error messages system
is implemented. Error codes should match the previous ones,
but are not necessarily correct now.