In regression datasets, show performance by quartile

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Wireframe:

Experiment:    dataset-foo/experiment-bar
Type:          regression
Predictions:   4000 (full dataset coverage)

Results:
- RMSE:                 4.1
- Mean abs error:       4.0
- Median abs error:     3.9
- 10-percentile err:    1.1
- 90-percentile err:    6.6

Quartile 1: 0.0 - 10.7
- RMSE:                 5.2
- Mean abs error:       4.9
- Median abs error:     4.9
- 10-percentile err:    1.2
- 90-percentile err:    7.8

Quartile 2: 10.7 - 15.2
- RMSE:                 5.2
- Mean abs error:       4.9
- Median abs error:     4.9
- 10-percentile err:    1.2
- 90-percentile err:    7.8

Quartile 3: 15.2 - 20.6
- RMSE:                 5.2
- Mean abs error:       4.9
- Median abs error:     4.9
- 10-percentile err:    1.2
- 90-percentile err:    7.8

Quartile 4: 20.6 - 33.4
- RMSE:                 5.2
- Mean abs error:       4.9
- Median abs error:     4.9
- 10-percentile err:    1.2
- 90-percentile err:    7.8