Bootstraped value_set type
Added required headers
Added value_set_deinit()
Added ws_value_set_init()
Added ws_value_set_new()
Added ws_value_set_insert()
Added ws_value_set_remove()
Added ws_value_set_get()
Added ws_value_set_union()
Added ws_value_set_intersection()
Added ws_value_set_xor()
Added ws_value_set_is_subset()
Added ws_value_set_equal()
Added ws_value_set_cardinality()
Added ws_value_set_select()
Added src/values/set.c to CmakeLists.txt