Fixed up REPL support.
Set the script to auto-extract after download.

This way, one should never have to see the warning message when executing the
repl command against the compressed script.
Added Erlang REPL.
Updated the docs to include new REPL support.
Updated the shell make target to use lfetool.
Added missing PATH var.
Added new "tests clean" command.
Added EXPM install and fixed other installs.
Added "update deps" command.
Moved command docs into new manual.
Replaced manual install with lfetool install.
Various fixes.
Make improvements to LFE install command.
Removed obselete targets and updated some more.