add Null hash digest for performance testing
remove unused parameters
avoid compiler warnings by template specialisation
add single file server class and test program
bump version after adding Null digest and SingleFileServer class
generalise += operator for different length operands
avoid compiler warning by template specialisation in UnsignedInteger class
bump version after generalising += operator for different length operands
Merge branch 'master' into debian-launchpad
update dependency for launchpad