WIP: new skip command

[Skarlett]

Command

@bot skip <?: pos default: :: > <?: filter: default: None>

Pos arg

Python like list slicing

@bot skip skips playing song
@bot skip 1 skips playing track
@bot skip 1:5 Skips enqueued songs 1 to 5 (4) in sequence.
@bot skip :5 skips current + 4 songs enqueued.
@bot skip 0:5 skips current + 4 songs enqueued.
@bot skip 5 skips current + 4 songs enqueued.

More complex examples

@bot skip -1 skips last song enqueued.
@bot skip -1:3 skips starting from last song, until position 3.
@bot skip -1:-3 skips starting from last song, until position -3.

0 [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ] - queued
^         3          -3    -1
 \ - currently playing

Partition slices

@bot skip :: (or :) Remove everything
@bot skip 1:5:-1 skips starting from last the song enqueued, until position 5.
@bot skip -1:-3:-1 starting from next song, until position 3. (very confusing double rotate)
@bot skip 1::2 starting from next song, everything divisible by 2 will be removed
@bot skip 1::-2 starting from the last song, everything divisible by 2 will be removed

Filter

Regex

if position provided, only affect within exclusive range
weak regex search against track_name|artist|album

ID/Mention

if position provided, only affect within exclusive range

Remove based on who enqueued via raw ID or @mention