Choice of possible symbols

[sts10]

I realize now that my choice in the symbols that Phraze can use between words was decided a bit hastily. Here they are:

const CHARSET: &[u8] = b"!@#$%&*(){}[]\\:;'<>?,./_-+=";

Should I include more or remove any? If so which? I think it's right to exclude backtick, ~, |, and ^, as they sometimes are difficult to type on mobile devices.