added NaN test for acosh
updated nan test for acosh
updated agrad/fwd/acosh
added NaN tests for agrad/fwd/acosh
fixed NaN bug in agrad/rev/acosh and switched to no namespace version of acosh
updated bound tests for acosh
added NaN and derivative doc for acosh in manual
added NaN test for asin
added NaN test to agrad/fwd/asin
updated NaN test for agrad/rev/asin
switched to no namespace version of asin
updated bound tests for asin
added NaN and derivative doc for asin in manual
switched to no namespace version of asinh
added NaN test for asinh
added NaN and derivative doc for asinh in manual
switched to no namespace version of atan
added NaN tests for atan
added NaN and derivative doc for atan to manual
added NaN test for bessel_first_kind