Function adjustBeatmapStats

This function returns a Beatmap with properties adjusted to the chosen Mods without making a request to the servers

The properties are namely: total_length, hit_length, bpm, diff_size, diff_approach, diff_overall, diff_drain

Note that this function doesn't adjust diff_aim, diff_speed or difficultyrating! Making a request using getBeatmap() adjusts everything, if you need to adjust any of these three properties