a stream on Text's which keeps track of the last attribute put; new characters are added with those attributes.

instance vars:

characters - a WriteStream of the characters in the stream
attributeRuns - a RunArray with the attributes for the stream
currentAttributes - the attributes to be used for new text
attributesChanged - whether the attributes have changed since the last addition

	private-initialization
	initialize

	retrieving the text
	contents

	stream protocol
	nextPut: nextPutAll:

	access	top
	currentAttributes return the current attributes
	currentAttributes: set the current attributes
	size number of characters in the stream so far

	private-initialization	top
	initialize

	retrieving the text	top
	contents Answer all of the contents of the receiver.

	stream protocol	top
	nextPut: Insert the argument, anObject, as the next object accessible by the receiver. Answer anObject.
	nextPutAll: add an entire string with the same attributes

	instance creation	top
	new Answer a new instance of the receiver (which is a class) with no indexable variables. Fail if the class is indexable.