1.4.0 release

Auto merge of rust-lang#29326 - Charlotteis:patch-1, r=steveklabnik

The beginning of the work that needs to be done as part of rust-lang#28835.

:sunny:

1.3.0 release

1.2.0 release

1.1.0 release

1.0.0 release

1.0.0-alpha.2 release

1.0.0-alpha release

0.12.0 release