(math-nth-root-float, math-nth-root-float-iter): Replace variables
n, nf and nfm1 by declared variables.
(math-nri-n): New variable.
(math-nth-root-int, math-nth-root-int-iter): Replace variable n by
declared variable.
(calcFunc-log): Removed misplaced condition.
before their first use. Use `when', `unless'. Remove trailing
periods from error forms. Add description and headers suggested by
Emacs Lisp coding conventions.