The data structures here were changed from sets to dicts at some point,
with the sets now having different names - this would crash trying to
subtract two dicts.
This adds support for detecting incorrect version numbers and links
in the ports list.
Also, unlike before it doesn't parse the package.sh script but executes
it instead which allows us to detect syntax errors.
install-ports copys the necessary files from Ports/ to /usr/Ports. Also
refactor the compiler and destiation variables from .port_include.sh
into .hosted_defs.sh. .hosted_defs.sh does not exists when ports are
built in serenity
