'clean' compile for OSX
disabled c++ interface on OSX for now
adjusted sample makefile for OSX
fixed tabbing in xsys_darwin.c
fixed serial I/O on OSX!
updated sample for use on OSX - use /dev/cu.*
reversed clock_gettime() -> xsys_clock_gettime() changes
Merge branch 'osx'

OSX support is now 'working'
  - you may need to increase your file limit using the following command:
    - ulimit -n 1024
  - the C++ interface isn't being compiled at the moment
updated HISTORY to reflect OSX support