tools: Rewrite to be more generic

All tools have been rewritten to be less kernel-centered. The main
objective is to be compatible with all projects that uses Kconfig/Kbuild
as their build system.

It introduces new variables and directories without breaking
compatitbility with repositories built using yocto-kernel-tools from
http://git.yoctoproject.org/cgit/cgit.cgi/yocto-kernel-tools/

Signed-off-by: David Vincent <freesilicon@gmail.com>