Pretty error messages for input parsing issues

[Vlek]

It would be nice if the error handler can output nicely formatted messages to point directly to the operation that caused the parser not to be able to work.

Example:

An exception occurred attempting to parse the input:
1 +
  ^
The addition operator expects a left and a right number.

[Vlek]

I think this is the way to do it: https://pyparsing-docs.readthedocs.io/en/latest/pyparsing.html#pyparsing.ParserElement.setFailAction

Already added a stub to the parser for an overall fail catch.