Fix copyf() in set for next version of libreset

The next version uses `void*` instead of `void const*` as
return/argument type.
Merge pull request #150 from matthiasbeyer/fix-for_next_libreset

Fix copyf() in set for next version of libreset
Adjust interface for ws_logger_context
Add implementation for ws_object_log()
Fixup: Context comes first
Fixup: ws_object_log() implementation: Context comes first
Fixup: Locking in ws_object_log()
Change naming: "dump" instead of "log"