Fix for *COPY finishing too early with files > 2G
Robert Sprowson authored
Same drill, V was being set or not preserved when it shouldn't or should be. In light of this all locations that do CMP/SUBS/ADDS involving fileptr/extent/anything ending in size or length have been reviewed and ammended where needed.
Trim some dead code.
Discard 'Version' file.

Version 2.70. Tagged as 'FileSwitch-2_70'
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