Avoid interleaving nREPL port info printing

Occasionally this was doing things like:

    user=> nREPL server started on port 56759
    (+ 1 1)
    2
Tidy up user.clj and help.clj.
Remove compatibility shims and warnings in preparation for 2.0.0.
Update news.
Allow for $LEIN_TRAMPOLINE_WARMUP.

[ci skip]
Bump reply for (exit) fix
fix bug when adding exclusions to dependencies with :displace metadata
a typo
Merge pull request #848 from jaceklaskowski/master

Fix for a typo
don't need a meta-merge to combine exclusion
Fix font-lock in bin/lein
Remove deprecated conj-dependencies function.
Accept ^:replace metadata on *env*; don't always want to merge.
Accept optional not-found arg in lookup-alias.
Better docstrings in leiningen-core.
Move AOT of :main into uberjar task. Remove :skip-aot.
Check Clojars releases repository instead of classic. Fixes #241.
Fix usages of when for return values.
Fix global exclusions test broken by meta-merge changes.
Fix error message when there's an arity mismatch in apply-task.