feature request: add sorting option in reshape long to wide transformation

[aborruso]

Dear @johnkerl ,
if I have

i,k,v
0,1,24.6659732638166
0,2,0.0771928403914854
0,3,17.1480573249446
0,4,4.58986335417567
0,5,54.8231067125631
1,0,1.11373416732727
1,2,650.147498986054
1,3,410.298565685827
1,4,1.72819356852476
1,5,9.43866767144718
2,0,0.000744447881092356
2,1,3796.81481074326
2,3,11032.9065659285
2,4,123.985540231058
2,5,197.189275372119
3,0,0.333937791717926
3,1,2403.31993964283
3,2,27512.0684265086
3,4,102.786833201422
3,5,224.520532630013
4,0,0.0334475453616899
4,1,0.0732440869183646
4,2,27.1453052119393
4,3,40.6457880530668
4,5,317.415260872447
5,0,0.155052216785343
5,1,34.9688187932276
5,2,6.86480543048321
5,3,24.5582674726038
5,4,42.0338516988724

and I run mlr --c2p --barred then reshape -s k,v then unsparsify input.csv I get

+---+--------------------+--------------------+------------------+------------------+------------------+----------------------+
| i | 1                  | 2                  | 3                | 4                | 5                | 0                    |
+---+--------------------+--------------------+------------------+------------------+------------------+----------------------+
| 0 | 24.6659732638166   | 0.0771928403914854 | 17.1480573249446 | 4.58986335417567 | 54.8231067125631 |                      |
| 1 |                    | 650.147498986054   | 410.298565685827 | 1.72819356852476 | 9.43866767144718 | 1.11373416732727     |
| 2 | 3796.81481074326   |                    | 11032.9065659285 | 123.985540231058 | 197.189275372119 | 0.000744447881092356 |
| 3 | 2403.31993964283   | 27512.0684265086   |                  | 102.786833201422 | 224.520532630013 | 0.333937791717926    |
| 4 | 0.0732440869183646 | 27.1453052119393   | 40.6457880530668 |                  | 317.415260872447 | 0.0334475453616899   |
| 5 | 34.9688187932276   | 6.86480543048321   | 24.5582674726038 | 42.0338516988724 |                  | 0.155052216785343    |
+---+--------------------+--------------------+------------------+------------------+------------------+----------------------+

The fields order is FIFO, and then I have 1,2,3,4,5,0 order.

It would be great to have here, without the need to add another verb, the option to enter a field sorting (it could be natural sorting or ascending or descending). In example to have the option -t and -tr.

Thank you

[aborruso]

Thanks to @pigreco for stimulating this idea and having made me discover this #1645