remove redundant trait information from export

[estebanlm]

when exporting a class with traits, I have this output:

Class {
	#name : #BlPoint,
	#superclass : #Object,
	#traits : 'TBlDebug',
	#classTraits : 'TBlDebug classTrait',
	#category : 'Bloc-Basic-Math'
}

The classTraits section is redundant (and is actually not needed to rebuild the class). This section has sense when there are rules that modifies the trait composition, but otherwise is cleaner not including it.