Moved system info into its own utility, so we can use in in test suite too.

Robustness fixes in test suite machinery. Added a module-level INSTALLED flag, which can be set to false if the test suite is being run in-place (without ipython having been installed at all). This is because how we call and import things must be done differently depending on whether the code is installed or is being run in-place. The only ones that can know this reliably are the entry-point scripts, so those are responsible for setting this flag. Also made the code that validates ipython in subprocesses report errors better, by checking stderr for errors before validating stdout output, as anything on stderr will be likely informative of the real problem.

Inform user at install time of minimal python requirements if not met. Fixes: https://bugs.launchpad.net/ipython/+bug/505090

Give good error message when starting tests if nose is missing.

Include iptest.py in MANIFEST so it gets shipped.

Doc updates to testing to reflect recent changes. Updated revnumber to push an updated testing release out for this branch.

Added %exit, %quit and %Quit as magics for consistency.

Make the test suite runnable without X11 connections. This fix makes the test suite work in settings like a screen session that can import but not initialize GTK.

Fix tests to return consistent results regardless of how they are called. Now, calling: - 'python iptest.py' from source dir or from src/IPython/testing should give the same results - 'python iptest.py IPython.SOMETHING' from either place should also give the same results.

Comment out accidentally left over 'raise'. This function promises NEVER to raise an exception, I was propagating it out while debugging some odd behavior with __builtins__ and left it accidentally in place.