Removed the ineffectual run-in-memory option - everything now runs in memory
Removed obsolete extract functions that have been combined into a single extractor
Renamed ExtractEverythingFromWorkbook to ExtractDataFromWorksheet for greater accuracy
Removed unused VersionedFileNotFoundException definition
Removed the obsolete intermediate_directory option
Reordered excel_to_x so main method is first
Refactored and renamed a_good_set_of_cells_that_should_be_settable_at_runtime
Removed redundant guard around work_out_which_named_references_can_be_set_at_runtime
Added documentation to filter_named_references
Tidied up set_defaults
Reordered and documented excel_to_x methods