ASCII notation

• all ascii notation is marked "only parsing" so this PR shouldn't change anything for anyone using only unicode notation.
• the algorithm for creating an ascii notation is pretty simple.
  • \ast -> * (not for separating conjunction)
  • \triangleright -> |>
  • \vee -> /
  • \wedge -> /\
  • \forall -> forall
  • \exists -> exists
  • separating conjunction -> **
• we're using notation scopes to resolve ambiguities

Closes #270 (closed)