Showing QrCodes for faster access to Read/Write URLs

Hi,

I found socrates pretty awesome. When I played around a was bored by typing the URLs into my smart phone manually. That's why I've created an extension for it.

There are two new buttons, showing a QrCode for accessing the read or write URLs by simply scanning the code.

Technically I've inserted the QR Code Generator from Kazuhiko Arase, which is also MIT licensed. See libs.js comments for details.

Also, because I don't have a license for using SymbolSet fonts, I've did a guess that the class 'ss-squares', maybe exists. Nevertheless, the codepoint in the source file is correct. You may adjust the name to fit the class name manually, please.

Thanks in advance.

Best regards
Martin