Autoreload verbosity

We introduce more descriptive names for the %autoreload parameter:

• %autoreload now (also %autoreload) - perform autoreload immediately.
• %autoreload off (also %autoreload 0) - turn off autoreload.
• %autoreload explicit (also %autoreload 1) - turn on autoreload only for modules whitelisted by %aimport statements.
• %autoreload all (also %autoreload 2) - turn on autoreload for all modules except those blacklisted by %aimport statements.
• %autoreload complete (also %autoreload 3) - all the fatures of all but also adding new objects from the imported modules (see IPython/extensions/tests/test_autoreload.py::test_autoload_newly_added_objects).

The original designations (e.g. "2") still work, and these new ones are case-insensitive.

Additionally, the option --print or -p can be added to the line to print the names of modules being reloaded. Similarly, --log or -l will output the names to the logger at INFO level. Both can be used simultaneously.

The parsing logic for %aimport is now improved such that modules can be whitelisted and blacklisted in the same line, e.g. it's now possible to call %aimport os, -math to include os for %autoreload explicit and exclude math for modes all and complete.