To-do list for Tie::MmapArray
=============================

* if no mode options are specified and the file is read-only then the
  mode should default to read-only (i.e. Do The Right Thing)

* use ftruncate to extend file size (where available)

* work out what should be done about extending mmaped arrays

* write more rigorous test cases

* tidy up documentation

* Win32 support
