Add arguments to fill polygons and set fill alpha for transparency

[abidawson]

Closes #13

[ricardo-bion]

Hi @abidawson, thanks for the PRs. It looks like this one has some conflicts. Can you try to rebase resolve?

[zh-Bian]

Hi, I found the file was conflicting. Ifound the update of the ggradar.R in https://github.com/ricardo-bion/ggradar/blob/8dae943d53da227922894bf980c829f694f9e7dd/R/ggradar.R. However, the file of ggradar.R did not update in the "Code"/R. I tried to change the code locally and reinstall to Rsutdio, but it didn't work. I sincerely hope that you can update the file in the "Code".Thank you!@abidawson @ricardo-bion @gousiosg @eknud

[ricardo-bion]

@tonyy0001 Is it worth resolving these conflicts and merging this one?

[tonyy01]

@tonyy0001 Is it worth resolving these conflicts and merging this one?

Thank you for your merging! It is an incredible project!

I have included these and all of the past features in my tidyverse style code. However, I have changed some of the variable names based on it and for readability as well as logical coding, so the code can be a little bit different from the original one. And that's the reason why I created another R file instead of making changes to the original one. I sincerely hope the users could adapt to the new function step by step, as it is more logical and easier for developers to contribute to it.