* window: use const references instead of copies
use const references instead of wasteful copies and make the = operator
check for self assignment and return early. also use const in all the
other operators.
* listener: pass std::function as const reference
instead of copies pass the std::functions as const references.
* config: dont unnecessarily convert to c_str
getHyprlangConfigValuePtr wants an std::string and we already have an
std::string, dont convert it to a c_str only for it to be converted back
to an std::string.
* buffer: pass attributes as const reference
pass attributes as const reference instead of copies.
