Create trait FASTTVariableDeclarator (and FASTTWithVariableDeclarators ?)

[NicolasAnquetil]

FASTTVariableDeclarator would have relation to:

• variable declared
• optional initial value (an expression)

mainly used in VariableDeclarations

[NicolasAnquetil]

example copied from FASTFortran (itself copied from FASTJava):

	((tWithDeclarators property: #declarators) comment: 'variables declared')
	<>-* (tVariableDeclarator property: #parentDeclaration).

	((tVariableDeclarator property: #expression) comment:
		 'Expression assigned to the variable declared')
	<>- (tExpression property: #variableDeclaratorOwner) .

	((tVariableDeclarator property: #variable) comment:
		 'The variable that is being declared')
	<>- ((variable property: #parentDeclarator) 
			comment: 'The declaration of this variable').