(cos_release_symbol): Treat `composition' as a builtin symbol.
(cos_string_ent_composition): New variable. (cos_symbol_ent_composition): New variable. (cos_Qcomposition): New variable. (cos_intern): Setup `composition'.
(cos_release_symbol): Add check for builtin symbols.
(cos_retain_symbol): Don't retain recursively. (cos_symbol_p): New function. (cos_symbol_table_intern): Check type of each entry of the hash; use `cos_retain_object' for the returned symbol. (cos_print_symbol_table): New function.
(cos_make_symbol): Use `cos_retain_object' for `obj->name'. (cos_retain_symbol): New function.
(cos_string_ent_nil): New variable. (cos_symbol_ent_nil): New variable. (cos_Qnil): New variable. (cos_string_ent_t): New variable. (cos_symbol_ent_t): New variable. (cos_Qt): New variable. (cos_intern): Setup `nil' and `t'. (cos_symbol_table_grow): Release old `table->data'.
New files.