* Make file number optional if input or output file.  Fix #481.  Support I:1 and O:2 etc.   * Added support for a numeric subelement.  Fix #479. (#483).  Should allow sub-elements so that you can get to the IO files and their individual data.* Fix #486. (#487).   String size changes (larger) failed on Omron because it does not reserve the maximum string size in the data it sends to the library.   Now when you call plc_tag_set_string() it will try to resize the tag buffer.   Fixed with #488.* Added atomic flag and checks to aid in making all sessions terminate when the library is shutting down. Fix #450.* plc_tag_set_string() feature additions (#488).   Setting string can change tag data buffer size.  And added flag, allow_field_resize, to suppress change.  Needed because the change for adjusting the buffer size could break code that is not aware of it.* Added msp response size check before adding new requests to msp with allow_packing=1 and fragmented reads disabled (#489).   This should allow more requests to be bundled together for Omron PLCs.  This is a work in progress and Phil has done a lot of work here.---------Co-authored-by: Phil Smith