nbb 1.20.x
  * Automatically call autoreconf for GNU make users.
  * Implement new command 'nbb help <command>'.
  * Implement global nbb options --vcs, --build-system, --dry-run.
  * Implement new command 'nbb config <option> [<new-value>]'.
  * Implement new command 'nbb init'
  * Implement new command 'nbb configure'
  * Implement new command 'nbb build'
  * Implement new command 'nbb install'
  * Implement new command 'nbb make [...params...]'
  * Refactor python module nbb_lib.py into nbblib/*.py
  * Miscellaneous build fixes related to move to standalone nbb.
  * Handle a few more corner cases with nested source trees.

nbb 1.20
  * Initial standalone version of nbb.