Improve documentation of mathematical functions

[HertzDevil]

Adds better documentation to the functions from the Math module. Unfortunately, this means the module no longer uses macros to quickly generate those LibM wrappers.

Also changes the parameter names of some functions, for consistency with either similar functions or other overloads:

• Math.atan2(value1, value2) => Math.atan2(y, x)
• Math.log(numeric, base) => Math.log(value, base)
• Math.besselj(value1, value2) => Math.besselj(order, value), ditto for .bessely
• Math.ldexp(value1, value2) => Math.ldexp(value, exp)
• Math.scalbn(value1, value2) => Math.scalbn(value, exp)
• Math.exp(z : Complex) => Math.exp(value : Complex), ditto for the Complex overloads of .log, .log2, .log10, and .sqrt

This could break code that uses named arguments for these mathematical functions. They are probably very rare though.

[HertzDevil]

Technically there could be proper deprecation for the old parameter names, e.g.

module Math
  @[Deprecated]
  def atan2(*, value1, value2)
    atan2(value1, value2)
  end

  @[Deprecated]
  def atan2(value1, *, value2)
    atan2(value1, value2)
  end
end

Is this necessary? How do we approach this kind of breaking changes in general?

[straight-shoota]

Yeah, that would be the proper way. But I don't expect anyone would actually pass named arguments for these Math methods, especially considering they weren't very soundly named.

[bcardiff]

FWIW I would not consider this a breaking-change. I don't expect the named arguments of these methods to be used that way.