v0.5.0

• Add nest operator: \ of algebra.
• Remove GeomElement.groupBy, which is replaced by nesting.
• Force labels always above graphics in an element.
• Rename All function properties to nouns.
• Fix a scale fommatter generic bug: #22.
• Constrain flutter version to '>=2.4.0 <2.6.0' for ScaleUpdate.delta: #21.