Add support for quantile and quantileIf functions #19

Job	Run time
3.7 CH=23.8.4.69	57s
3.7 CH=22.5.1.2079	1m 4s
3.7 CH=19.3.5	47s
3.7 CH=18.14.9	47s
3.8 CH=23.8.4.69	41s
3.8 CH=22.5.1.2079	36s
3.8 CH=19.3.5	28s
3.8 CH=18.14.9	33s
3.9 CH=23.8.4.69	36s
3.9 CH=22.5.1.2079	43s
3.9 CH=19.3.5	40s
3.9 CH=18.14.9	33s
3.10 CH=23.8.4.69	36s
3.10 CH=22.5.1.2079	35s
3.10 CH=19.3.5	38s
3.10 CH=18.14.9	29s
3.11 CH=23.8.4.69	39s
3.11 CH=22.5.1.2079	46s
3.11 CH=19.3.5	27s
3.11 CH=18.14.9	31s
3.12 CH=23.8.4.69	1m 7s
3.12 CH=22.5.1.2079	58s
3.12 CH=19.3.5	51s
3.12 CH=18.14.9	58s
Indicate completion to coveralls.io	5s
	17m 5s

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