enable pretty-printer, disable pretty-printer.
* NEWS: Mention them.
* data-directory/Makefile.in (PYTHON_FILES): Add gdb/printing.py,
gdb/command/__init__.py, gdb/command/pretty_printers.py.
* python/lib/gdb/__init__.py: Install pretty-printer commands.
* python/lib/gdb/printing.py: New file.
* python/lib/gdb/command/__init__.py: New file.
* python/lib/gdb/command/pretty_printers.py: New file.
doc/
* gdb.texinfo (Pretty Printing): Expand into three sections,
introduction, example, and commands.
(Python API): Delete section Disabling Pretty-Printers, merge into
Selecting Pretty-Printers.
(Writing a Pretty-Printer): New section. Move the pretty-printer
example here, and reformat to match python coding style. Add a second
example using the gdb.printing module.
(Python modules): Add gdb.printing.
testsuite/
* gdb.python/py-pp-maint.c: New file.
* gdb.python/py-pp-maint.exp: New file.
* gdb.python/py-pp-maint.py: New file.
