Auto-generate 'libraries' folder if not present

On a number of occasions, especially when people are using Arduino for the
first time, we have observed a lot of frustration in the process of
installing libraries.

Common issues include: 
  - Not being sure where to put the directory
  - Not being sure what to name the directory
  - Not being able to find a folder called "Sketchbook" to put it in
and so forth.

These issues are a side effect of the transition at Arduino 0017; before
that, there was a pre-existing libraries folder with items in it.

To address this I'd like to suggest that Arduino automatically generates a
SKETCHBOOK/libraries folder if one is not present. 

Possibly, it would also be a good idea to include a README file in that
directory that says something like "This folder is where you place Arduino
library folders.  To install one, unzip it and move it here.  Then, restart
Arduino. See also: http://arduino.cc/en/Reference/Libraries"

It may also be a good idea to include similar folders for boards and
programmers, since they serve analogous purposes.

Original issue reported on code.google.com by windell@oskay.net on 8 Feb 2010 at 9:44

Merged into: #986

jung6717 / arduino

Auto-generate 'libraries' folder if not present #202