Interfaces for working with input/output tabs.

A few other parts of the IDE use the Output Window to display messages from a running process or operation of some sort - for example, the progress of compilation, or status messages from the Java parser.

The Output Window is organized into tabs, each of which is capable of handling both input and output. `IOProvider.getIO(String, boolean)` will get the `InputOutput` handle for one tab of the output window. Frequently, though, such a tab will be created by IDE implementation code and passed to your code automatically.