Using {} instead of <> for .ascii value to be or'ed

[tomgalvin594]

Currently, the 0xSCA syntax uses angled brackets to enclose the value to be or'ed with an ascii string. This makes parsing the assembly file much harder as the angled brackets are also used for greater than and less than. I propose instead that we use curly brackets to denote the value to be or'ed. This makes the syntax a bit more context free, which allows for easier parsing.