Add ws_string_init_from_str to header
Add ws_string_init_from_str to string.c
Rewrite ws_string_dupl to call ws_string_init_from_str
Simplify string initialization in union.c
Merge pull request #352 from xVin/Add-ws_string_init_from_str

Add ws string init from str
Add ws_event interface definition + stubs
Add implementation for ws_event_init()
Add implementation for deinit callback
Add implementation of ws_event_get_name()
Add implementation for ws_event_get_context()