Current SRC definition only picks up main.go, not all golang source code
of the project. Fix so that 'make fmt" and 'make simplify' can work as
expected.
ith a fresh checked out k3d tree without required tools installed, Any make command gives the following error message:
Makefile:71: *** recipe commences before first target. Stop.
Basically, the section around line 71 are not properly formed makefile rules. This error is hidden when required tools
are installed. The error can be re-exposed with the "make extra-clean" command.
The install-tools target is intended to be invoked when installing the development tree for the fist time.
The extra-clean target removes the dependent packages that k3d requires. This makes testing
makefile rules that install those packages easier.
This target helps to expose a bug that the next patch fixes.
