Add IsNull() to class CAutoFile and remove operator !
Chain::SetTip return type to void
Fixes for missing boost tuple.hpp header include.
CAutoFile: Explicit Get() and remove unused methods

Also add documentation to some methods.
Merge pull request #5104

b7ae2c1 Chain::SetTip return type to void (21E14)
Merge pull request #5110

a3c26c2 Fixes for missing boost tuple.hpp header include. (randy-waterhouse)
Merge pull request #5108

a873823 CAutoFile: Explicit Get() and remove unused methods (Wladimir J. van der Laan)
fef24ca Add IsNull() to class CAutoFile and remove operator ! (Ruben Dario Ponticeli)
Merge remote-tracking branch 'official/master'