In this patch, the tested zasync stream is being introduced. This class is the
implementation of simple, point-to-point IPC between two processes. A process
can be connected to by multiple other processes, and can itself connect to
multiple other processes, but things like multicast to a named segment of
subscribers are not supported.

Implemented a small library of code for doing IPC data transfer of typees
BUFFER, MAP_AND_COPY and MAP_AND_READ. MAP_AND_READ currently doesn't work
perfectly because I have yet to decide how to cleanly relay the offset into the
mapped page at which the recipient process can read the transferred data.

* walkerPageRanger:
  * Introduced destroyNonsharedMapping(): tears down an unshared mapping.
  * New method: createSharedMappingTo(): Allocates pages for, and creates a
    mapping to a designated area in another process' addrspace.
* x86-32 Page fault handler now tries for pmem allocation a max of 4 times.
* New namespace ipc within messageStream.h/cpp. Contains the implementations of
  the functions to do with IPC data transfer setup and dispatch.
* zasyncStreamC::send() now accepts a privateData argument, which is returned to
  the sender through zasyncStreamC::acknowledge(). This is not guaranteed by the
  kernel, but is to be negotiated between the participant processes.