Improvements to sync and new-fb

Main features:
* Changed rebase to be the default for sync
* Added autofetch to new-fb
* Added branch name to sync

Changes:
* Improved the resiliency of sync
* Removed rerere suggestion
* Removed interactive to-master
* Extracted sync functionality into library
Updates to docs and help system

Moved over to use the "native" git help system using man pages.
Added local-build script