fix(readcomicOnlineli): Resolves #340

[lmagdanello]

Hello,

I noticed some problems when downloading readcomicOnline.li. I debugged a bit and realized there were some problems:

1. I analyzed the full_series function and noticed that the listing_table was empty. After some testing, I checked self.appended_headers from ReadComicOnlineLi: these additional headers were breaking the connection to the site. I removed some of them and added a way for comic-dl itself to check which platform it is running on (Linux, MacOs, Windows...). This resolved access;

2. After this, I realized that the regex in single_chapter that creates the list of comic images had an error. It used double quotes instead of single quotes to filter lstImages.push:

3. With this list of images, I created a function called beau, inside get_image_links, which is used to decode URLs that have been obfuscated. In the end, it returns a list of image URLs.

I ran some tests and verified that the readcomicOnline.li download is working again.

Can you review it?