Bug: Multiplicity 0..* is displayed as * in class diagrams #142

Description

When creating a class diagram in Modelio, setting an association's multiplicity to 0..* results in the diagram displaying only * instead of the full multiplicity.

This makes it impossible to visually distinguish between 0..* and 1..*, even though these multiplicities have different meanings in UML.

Steps to Reproduce

Create a class diagram.

Create an association between two classes.

Set one association end's multiplicity to 0..*.

Observe the multiplicity displayed on the diagram.

Expected Behavior

The multiplicity should be displayed as 0..*, indicating that zero or more instances are allowed.

Actual Behavior

The multiplicity is displayed as *, omitting the lower bound (0).