3.9.0

This is a release that both adds a few shell-related features, but more importantly fixes some significant bugs.
First the bugs:

• Fix performance regression in compiler around behaviours, which sometimes resulted in massive slowdowns
• Fix common test logging output with OTP-21.2 and logger when multiple crashes happen
• Fix handling of updated hrl files not triggering a recompile in tests when they are changed
• Unhang the logger when swapping the TTY in shell in OTP-21.1 and later
• Use double quotes in git shell command on Windows to prevent failures
• fix case clause handling when fetching hg dep
• Reorder rebar3 tree output on umbrella apps to be predictable
• update templates to remove deprecated maintainers field

The shell features are some workarounds and niceties related to known limitations:

• Support setting shell hot code loading blacklists to prevent frequently crashing applications from being killed
• Add --relvsn and --relname to rebar3 shell to allow selecting which release definition to use