Clean Up System Call Interface

[dthain]

Rework the system call interface to more elegantly handle the notion of hierarchical containment. The guiding principles should be:

• Any creation of a kernel object should always be relative to a parent object descriptor.
• The root process begins with file descriptors describing the root window, root filesystem, etc.
• Child processes should inherit descriptors from the parent, and only be able to reduce privilege.

For example, instead of these Unix-like calls:

fd = open(path,mode)
success = mkdir(path)

We should have these parent-relative calls:

fd = opendir( parent, name ) 
fd = mkdir( parent, name )

Before coding, spend some time to carefully design the system call interface, propose the change, and get some feedback from the rest of the team.