Merge pull request #1 from Fraser999/address_allocation

Updated NodeId::CommonLeadingBits and added unit test.
Merge pull request #2 from Fraser999/address_allocation

Further work on address_space_tool.
Merge pull request #3 from Fraser999/address_allocation

Added leeway parameter to address_space_tool.
Merge remote-tracking branch 'origin/address_allocation' into address_allocation
Improved speed of NodeId::CommonLeadingBits.