Allow derivative of Bessel functions with respect to order

[kcrisman]

There are at least some formulas for Bessel derivatives with respect to order (also here), though some of their forms are not particularly helpful without some other things working properly like series of digammas (apparently).

Component: calculus

Issue created by migration from https://trac.sagemath.org/ticket/20615

[kcrisman]

Description changed:

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+++ 
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-There are at least *some* [formulas for Bessel derivatives with respect to order](http://dlmf.nist.gov/10.38), though [some of their forms](http://mathoverflow.net/questions/4019/derivate-bessel-function-with-respect-to-order) are not particularly [helpful](http://functions.wolfram.com/Bessel-TypeFunctions/BesselK/20/01/01/) without some other things working properly like series of digammas (apparently).
+There are at least *some* [formulas for Bessel derivatives with respect to order](http://dlmf.nist.gov/10.38) (also [here](http://dlmf.nist.gov/10.15)), though [some of their forms](http://mathoverflow.net/questions/4019/derivate-bessel-function-with-respect-to-order) are not particularly [helpful](http://functions.wolfram.com/Bessel-TypeFunctions/BesselK/20/01/01/) without some other things working properly like series of digammas (apparently).

[kcrisman]

comment:2

Thanks to Grant Ellis for this link and paper title with some information on more derivatives:

Higher derivatives of the Bessel functions with respect to the order