Change documentation for how to log using sky_tool

Actually make the raw examples work again

In my previous patch, I forgot to fill in the other diagonal entries in the
device transform matrix.

Remove all clients of sky.view.picture

Everyone uses sky.view.scene now. This patch also cleans up the raw examples
and makes them follow a consistent pattern.

Guard IOSDevice logs

Add sky_tool logs command

Initial boss fight in demo game

Improvements to demo game

Move widgets and rendering inside src

Improves on demo game balance and adds levels for lasers

Code outside of package:sky should import this code using

package:sky/rendering.dart
package:sky/widgets.dart

Moving this code into the "src" directory is a convention that signifies that
and it cleans up the generated dartdoc because the libraries in the src
directory aren't included in the generated documentation. Instead, the classes
are documented in the widgets.dart and rendering.dart libraries.

Very simple so far. This schedules an alarm to fire once a day, kicking
off a service that downloads a new app.skyx from a hardcoded URL. The
new skyx replaces the current one.

Restore PageableList itemsWrap:true

Makes PageableList with itemsWrap:true work again.

Plumbed the itemsWrap parameter through to HomogenousViewport.

Fixes issue #877.

Fixes issue in sprite constraint

Makes PageableList with itemsWrap:true work again.

Plumbed the itemsWrap parameter through to HomogenousViewport.

Fixes issue #877.

This CL deletes a bunch of unused IDL files and removes some dead code in the
engine.