* version 5.1.0 of Chicken is out.
* Makefile goes from GPLv2 to GPLv3+
* other small enhancements to Makefile

Signed-off-by: Jeronimo Pellegrini <j_p@aleph0.info>

Signed-off-by: Jeronimo Pellegrini <j_p@aleph0.info>

Maintainer: myself ( Jeronimo Pellegrini <j_p@aleph0.info> )

Compile tested: compiles on x86_64, target mips (AR7xxx), OpenWRT master
  and OpenWRT 18.06.2
Run tested: on AR7xxx (TP-Link Archer C7 v.4)

Description:
This is an efficient Scheme interpreter, which comes with several
modules for networking, filesystem access, and other useful tasks.
It can be used as scripting language for automating tasks, by users
who prefer dynamic functional languages over imperative or
object-oriented ones.