Though getOutput() is what first came to mind, I do not particularly
like the name, partly because it is used in many, many places as a
method that returns an OutputPage object.
* Renamed the method to __toString(). This is appropriate because
each instance, at any given time, corresponds to a single string
value (and exceptions cannot occur during this conversion).
* Removed unnecessary variables from ApiQuery and ExportTest. In
these and most other cases, it should no longer be necessary to
call getOutput() explicitly.
Change-Id: Icf202743d1f332f8981338f42eb6e3e5a04abdf1
Specifically, it is not necessary to use output buffering functions
to capture XML generated by the export code because it is already
possible to set the "output sink" object to be used.
* Created a DumpStringOutput class, which appends all output to a
string property rather than printing output immediately.
* Used that class, instead of ob_start() and ob_get_clean(), in
ApiQuery and ExportTest.
Change-Id: I238f5d5ec7fd442c845b25cb59ef81ac3285099f
