Declare all Makefile targets as phony

This ensures that they do their work without paying attention to
dependency tracking.
Refactor types to move logging out of Xcode.swift
Add ProjectEvent type to remove Project logging
Aggregate stderr into a signal error by default
Merge pull request #103 from Carthage/no-logging-in-carthagekit

Stop writing console messages in CarthageKit
Merge branch 'master' into self-hosting-carthage