Allow IPv6 host addresses

Syntax examples:
  fe80::1111:2222:3333:4444
  user@fe80::1
  user@[::1]:2222 (square brackets are necessary for non-standard ssh port number)
Add IPv6 support for rsync project synchronization
Add some IPv6 related comments
Add test coverage for IPv6 related functions
fix typo
A friendlier default password prompt. Displays the user the password is being asked for.
Better language for password prompt.
Merge pull request #624 from pacemkr/b0f41ec86fbaa9e1da179c7061f956ec1394d551

Include username in default password prompt
Backport 08c5a6a from master and add changelog, test fixes
Merge branch '1.3' into 1.4

Conflicts:
	docs/changelog.rst
Merge branch '1.4'
Clean up hide/show if exceptions occur.

Fixes #625
Merge branch '1.3' into 1.4
Merge branch '1.4'
Enhance installation documentation a bit
Merge branch '1.3' into 1.4
Merge branch '1.4'
More tweaks
Merge branch '1.3' into 1.4
Merge branch '1.4'