Add support for quantile and quantileIf functions #28

Job	Run time
3.7 CH=23.8.4.69	58s
3.7 CH=22.5.1.2079	1m 4s
3.7 CH=19.3.5	1m 1s
3.7 CH=18.14.9	52s
3.8 CH=23.8.4.69	44s
3.8 CH=22.5.1.2079	35s
3.8 CH=19.3.5	37s
3.8 CH=18.14.9	28s
3.9 CH=23.8.4.69	38s
3.9 CH=22.5.1.2079	34s
3.9 CH=19.3.5	29s
3.9 CH=18.14.9	31s
3.10 CH=23.8.4.69	35s
3.10 CH=22.5.1.2079	32s
3.10 CH=19.3.5	33s
3.10 CH=18.14.9	35s
3.11 CH=23.8.4.69	38s
3.11 CH=22.5.1.2079	37s
3.11 CH=19.3.5	41s
3.11 CH=18.14.9	25s
3.12 CH=23.8.4.69	1m 3s
3.12 CH=22.5.1.2079	57s
3.12 CH=19.3.5	54s
3.12 CH=18.14.9	52s
Indicate completion to coveralls.io	5s
	16m 58s

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