updated deprecated makedocs call: format; clean build dir; aligned code

[PaulXiCao]

• major change: updated makedoc call. format = :html is deprecated.
• minor
  • cleaning build dir by default is useful
  • aligned code

PS: this is in reference to issue #159 .

[simonbyrne]

Thanks @PaulXiCao. A few points:

1. I think this information would be better incorporated into the docstrings. These could then be grouped into headings as you've done here.
2. Whether there is a BigFloat implementation is really an implementation detail, i.e. you can write something like:

## Implementation details

- `Float32`/`Float64`: C standard math library (libm)
- `BigFloat`: [MPFR](https://www.mpfr.org/)

[PaulXiCao]

@simonbyrne I cannot find a good workflow. The documenter.jl does not use my uncommited docstrings. Do you know any way?

[simonbyrne]

Change to the docs directory, start julia with julia --project, then do ]dev ..

[PaulXiCao]

@simonbyrne could you give a short feedback on my commits?
I have done the following for all functions in erf.jl and ellip.jl

• added documentation
• cleaned the source code
• added tests for every possible case (data types and each piecewise definition)

My questions

1. Any feedback? Would you like something done differently?
2. If I do the same for other files would you pull it at some point?
3. Should I split my work into different merge requests or just keep pushing to this one?

[PaulXiCao]

Closed by mistake... facepalm

[simonbyrne]

Thanks, this looks really good!

[simonbyrne]

Looks much better, thanks!