Add flx-ido to the list of default packages
flx-ido does not exist but flx does

I had to change flx-ido to flx to avoid the following:

error: Package `flx-ido' is not available for installation
Merge pull request #357 from localredhead/master

flx-ido does not exist but flx does
Fix a typo
Refactor the window switching advice code
Add a few keybindings making use of the Super key
Remove a problematic keybinding
Revert "flx-ido does not exist but flx does"

This reverts commit 6821b1d79b13201fd467990016b92e09fa4f7ddf.
Merge remote-tracking branch 'bbatsov/master' into bbatsov-master