Concrete/Abstract Syntax for real literals

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>
Add real primitives

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>
Fix typo in test case

This was actually a syntax error.

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>
Switch to Parboiled parser

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>
Start with real-number test cases

Actually, 5 /r 2 should be a type error, but since we do not check
and since real literals are not yet handled in the code generator,
this will work for now.

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>
Actually implement some real-literal and op parsing

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>