Add parsing for ClassExpression

Signed-off-by: Maximilian Marx <mmarx@wh2.tu-dresden.de>
Fix Whitespace handling, Volume III

Also skip multiple adjacent comments, and skip after every bracketed
expression.

Signed-off-by: Maximilian Marx <mmarx@wh2.tu-dresden.de>
Fix prefixDeclaration

Don't require an extra closing bracket in prefixDeclarations

Signed-off-by: Maximilian Marx <mmarx@wh2.tu-dresden.de>
Fix annotationAssertion

AnnotationAssertion is not isomorphic to the other AnnotationAxiom
constructors, so don't use annotationAssertion'.

Signed-off-by: Maximilian Marx <mmarx@wh2.tu-dresden.de>
Introduce a type for Declaration

Signed-off-by: Maximilian Marx <mmarx@wh2.tu-dresden.de>
Implement all rules for Axiom

This completes the parser, and it now sucessfully parses a few real-world
ontologies.

Signed-off-by: Maximilian Marx <mmarx@wh2.tu-dresden.de>