Rename str2var to str_to_var and similar

Affects the Math class, a good chunk of the audio code, and a lot of other miscellaneous classes, too.

- `var2str` -> `var_to_str`
- `str2var` -> `str_to_var`
- `bytes2var` -> `bytes_to_var`
- `bytes2var_with_objects` -> `bytes_to_var_with_objects`
- `var2bytes` -> `var_to_bytes`
- `var2bytes_with_objects` -> `var_to_bytes_with_objects`
- `linear2db` -> `linear_to_db`
- `db2linear` -> `db_to_linear`
- `deg2rad` -> `deg_to_rad`
- `rad2deg` -> `rad_to_deg`

- `dict2inst` -> `dict_to_inst`
- `inst2dict` -> `inst_to_dict`

servers/audio/effects/audio_effect_eq.cpp

@@ -38,7 +38,7 @@ void AudioEffectEQInstance::process(const AudioFrame *p_src_frames, AudioFrame *
 	EQ::BandProcess *proc_r = bands[1].ptrw();
 	float *bgain = gains.ptrw();
 	for (int i = 0; i < band_count; i++) {
-		bgain[i] = Math::db2linear(base->gain[i]);
+		bgain[i] = Math::db_to_linear(base->gain[i]);
 	}
 
 	for (int i = 0; i < p_frame_count; i++) {