(homebrew) Add fuse.pc symlink

This addresses https://github.com/mxcl/homebrew/issues/22838
(framework) Fix error parameter handling in fusefm_mkdir
Add check for Xcode 5.0

The final release of Xcode 5.0 does not include OS X 10.9 SDK. OS X 10.9
support has been added in Xcode 5.0.1.
Update README.md

Add information about Xcode 5.0/5.0.1 and PackageMaker
Use /bin/cp instead of cp in PATH

Addresses issue https://github.com/osxfuse/osxfuse/issues/74
Use pkgbuild instead of PackageMaker to build installer packages
Remove re-distribution package
Check if prefpane is installed before trying to uninstall it
Bump version to 2.6.2