Scripts and documentation for building system images for our target platforms. The
goal is to help anyone checking out the right repositories, configuring a target
and build the images that are built by CI (in fact CI will use these scripts).

The central piece is a Makefile that helps to:

	* Git clone the necessary layers
	* Update/git pull --rebase all of them
	* Set-up the build as used by sysmocom
	* Configure .ssh/config for uploading to sysmocom
	* Do the upload
	* Clean after a build

The bblayers.conf is created from a template located in cfg/ and the local.conf
will be created by using Poky's oe-init-build-env and then files from cfg/common/*
and cfg/BOARD/*. Files will be sorted in their alphabetically sort order and first
come from the common directory and then the board specific one. At the end an include
directive will be issued.


Using the Makefile:

	$ make help
	...

Example of building everything

	# make install-ssh-config SSH_HOST=build-upload.foo.bar SSH_PORT=2342
	$ make setup-all V=1
	... git clone
	... git pull --rebase
	... creating build directories

	For the sysmobts firmware needs to be copied to the downloads directory.
	As a customer you should have received instructions for doing it and as
	an employee it should be mentioned in the wiki

	$ make build-all	# Build for all boards the default targets
	...

	$ make upload-all	# Make an upload to testing for all boards
	...

	$ make clean-all	# Clean the tmp directory for all boards
	...