Julia Package Note

method	ability	addition
Pkg.status()	show pkg
Pkg.installed()	get an array all pkg(name, array),
REQUIRE	all pkg are needed	# comment.
usage:Distributions 0.1	greater than or equal to 0.1.0
Pkg.resolve()	add pkg in REQUIRE
Pkg.update()	update all pkg
Pkg.pin(Pkg,version)	set the Pkg to a special version
@	it is a system-dependent requirement.	@osx Homebrew