This adds devel/arduino-bsd-mk which installs a make(1) makefile
(bsd.arduino.mk) that is used to build Arduino sketches from
the command line. It is designed to be a FreeBSD-friendly
alternative to the existing gmake based devel/arduino-mk port.
It includes a man page and optionally installs an example sketch
with an exmaple Makefile.

Reviewed by: matthew (mentor)
Approved by: matthew (mentor)
Differential Revision: https://reviews.freebsd.org/D13262