Chdir changes the directory so that all operations from now on are relative to the project we are working with.

CopyFile is a braindead simple function that copies a src file to a dst file.

NamePath just cleans a name and makes sure it's appropriate to use as a path.

NewFileMutex creates a new FileMutex using the given file as a file lock.

QnamePath just cleans a name and makes sure it's appropriate to use as a path.

WalkUp walks each file in path, passing the full path to `walkFn`.

FileMutex is a mutex that serializes both within and across processes.