refs #6362 Attempt to move the code responsible to ISaveable

into Kernel
refs #6362 Fixing ISavable
refs #6362 ISaveable modified to keep the information about its place

ISavable now knows about its position in file and works together with the DiskBuffer to identify the location of the data in the file.
refs #6362 Checked performance tests
refs #6363 MDBox test passes with modifications
refs #6362 MDGridBox test works

(without modifications)
refs #6362 Save made constant and special command is used to free mem

small changes to algorithms too to incorporate new logic of working
refs #6362 SaveMD works
refs #6362 Removed notuse disk buffer mode from MDWorkspace modes

All file based workspaces have to use disk buffer now. If the disk buffer size is set to 0, the data are saved to HDD (or discarded if not modified) as soon as they are free.
refs #6362 LoadMD tests work
refs #6362 SliceMD reconfigured to use write output buffer
refs #6362 Modified MDBoxBaseTest to reflect new work patterns
refs #6362 UseWrieBuffer meth is available on BoxController interface

and always reports true for export to python.
refs #6362 Commented yet unused file from cmake list
refs #6362 fixing Unix error
refs #6362 fixing Unix error (missing boost header)