Windows 10 Support

[errosica]

Thanks for this great extension! I read that you weren't sure if it worked on Windows. I tried it on my PC and all you need for Windows 10 support is to to add pdf2svg to the user's path. I guess it's obvious, but you might want to mention this in the docs.

I suggest that you have the program explicitly check for pdf2svg, and pass a simple error message if it can't be found. The existing python generated error message is quite cryptic (it's a file not found error message, which is generated since the svg file doesn't exist, since pdf2svg couldn't be found).