Cleanup #classes/#classesAndTraits

[jecisc]

Currently we have #classes/#classesDo:/#classesAndTraits/#classesAndTraitsDo: that are all returning classes and traits.

We discussed with Steph and Marcus and we don't like it. Here is what we would like to get:

P12

• #classes => Classes and traits
• #classesAndTraits => classes and traits

P13

• #classes => Deprecated toward #classesAndTraits
• #classesOnly => Classes
• #classesAndTraits => Classes and traits
• #traits => Traits

P14

• #classes => classes
• #classesOnly => Deprecated toward #classes
• #classesAndTraits => Classes and traits
• #traits => Traits

So we need to do this change one 2 Pharo version