handle nil and non-String objects in shellescape()
Prefixing
  added refactoring command
  added file generation commands
    xcproject binary links with frameworks from Xcode => better than xcodeproj gem

Baproj
  centralized location to specify project-wide settings
small update to _xcproject
import prefixing aliases for in precompiled header
fixes for prefixing file collection and generated pch path
_xcproject
minor changes to header templates