always allow SVGs on about:tor
On its highest setting, the security slider blocks SVGs on about:tor. But we would like to use them there. See ticket:25695#comment:31.
We will need to decide if this is safe. An argument can be made that allowing SVGs on built-in pages is not much different than allowing their use in the browser chrome.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information