Change ADTs to generate a copy_construct() that returns this, which should be our new default. Fix storing functions in vectors (lots of bugs here, with funciton types in templates, sizeof, returned by ref, etc. might have missed a few more, put in some warning comments

stdlib/adt_lower.krak

@@ -108,6 +108,7 @@ fun adt_lower(name_ast_map: *map<str, pair<*tree<symbol>,*ast_node>>, ast_to_syn
                                 if_stmt_inner->if_statement.then_part = assign_or_copy_construct_statement(our_option, their_option)
                                 block->code_block.children.add(if_stmt_inner)
                             }
+                            block->code_block.children.add(_return(func_this))
                         } else if (func->function.name == "operator=") {
                             var other = func->function.parameters[0]
                             block->code_block.children.add(make_method_call(func_this, "destruct", vec<*ast_node>()))