Agena Portable full changelog

`calc.xpdiff` and thus also `calc.differ`, with no specific epsilon value given in the function call, often had severe problems correctly computing the third derivative (and only this one), especially with roots and logarithms. This has been largely fixed at a slight decrease of accuracy with trigonometric functions, but with `calc.xpdiff` only. The accuracy of `calc.differ` with trigonometric functions is the same as before.
All issues with `calc.differ`, `calc.xpdiff` and `calc.diff` that occured on x86 Mac OS X with the previous release have been solved.
`math.epsilon` has again been slightly changed:
in the first form with method 0, it has been changed back to the version prior to Agena 4.2.3, returning Eps with |x| < 1 and a value greater than Eps otherwise;
in the first form with method 1, it now returns Eps with |x| < 0.0123927159 and a value greater than Eps otherwise;
the second form has been left unchanged.