BitBake "Hello, World!" Project

This is nearly the smallest, valid BitBake project that prints "Hello, World!" This is useful because:

1. It can serve as a simple basis from which to test and explore basic BitBake features.
   

2. It reveals what is fundamental to BitBake itself, apart from the superstructure that OpenEmbedded, Yocto, et. al. put on top of it.

This project has been tested against BitBake 1.15.2, which is what Yocto "denzil" uses. Here's the output:

$ ../BitBake/bin/bitbake  a
Parsing recipes: 100% |########################################################| Time: 00:00:00
Parsing of 1 .bb files complete (0 cached, 1 parsed). 1 targets, 0 skipped, 0 masked, 0 errors.
NOTE: Resolving any missing task queue dependencies
NOTE: Preparing runqueue
NOTE: Executing RunQueue Tasks
NOTE: Running task 1 of 1 (ID: 0, /home/pturley/Workspace/Hello/LayerA/a.bb, do_build)
NOTE: package None: task do_build: Started
Hello, World!
NOTE: package None: task do_build: Succeeded
NOTE: Tasks Summary: Attempted 1 tasks of which 0 didn't need to be rerun and all succeeded.

Some things to note:

1. This is not the smallest such BitBake project. For example, the DESCRIPTION and PV variables need not be assigned in a.bb. I set those variables because I wanted show-layers and show-recipes to display reasonable information.
   

2. Some of the variables set in bitbake.conf have "simplified" values. For example, you would not want to use these values if there were multiple recipes and you had to disambiguate the output from each of them.
   

3. On the other hand, all the variable assignments in bitbake.conf are essential to BitBake itself. If you remove any one of those assignments, BitBake will either declare an error or die (usually because some internal variable is set to None and the BitBake code can't handle it).