Add fns to stat output (isFile, etc)

[pfrazee]

Adds common methods to the output of the stat() call:

• isSocket
• isSymbolicLink
• isFile
• isBlockDevice
• isDirectory
• isCharacterDevice
• isFIFO

These functions were included in the output of hyperdrive's stat() call and I've got some code that depends on it. If you don't think this should be added I can find a way around it, but I thought I'd try this first.