Rolling statistics and regression

Toolset quant_stats: 3 tools.

Tool	What it does	Notes
`quant_rolling_stat`	Rolling (or, with no window, expanding) statistic of one dated series over a window of observations or a tenor such as ‘1m’ or ‘1y’: min, max, range, mean, root mean square, median, mode, sum, product, standard deviation, variance, z-score, winsorized values, percentile, percentile rank, or exponentially weighted standard deviation.
`quant_sample_series`	A random-walk sample series starting at 100 with standard normal steps, dated daily or by minute from or up to now; every call draws a new path.
`quant_linear_regression`	Ordinary least squares of one dated column on one to twenty others, on the dates where all are present (rows with missing or infinite values are dropped).

Inputs, limits and outputs are described in Fincept Quant. Full schemas: fincept_describe_tool.