fix fltk13-aqua_1.3.3-3 on Xcode 9
fix image-oct-2.2.1-3 to build against Xcode 9
With fink-0.42.0 out, there's now a java9 family of virtual packages. Assuming that Oracle isn't going to go back to having minor-versioned directories, that could be a dependency option which gives a deterministic build.
fix signal-oct-1.3.0-1 to build against Xcode 9
Added entries about what to do when a source tarball can't be found
Added section about replacing manual XFree86 installation.
Updated FAQ to include how to replace manual XFree86 install with fink packages.