Proposal: remove the 'create new .lyx directory?' popup

[Jean-Marc Lasgouttes]

I plan to remove the popup asking new users whether a new directory
should be created for them, and add some information to splash.lyx
indocating that a .lyx directory has been created. This seems cleaner
to me. This would mean that using -userdir with a nonexisting
directory would silently create a new one and run configure in it.

Is that OK?

JMarc