Remove branches configuration from .travis.yml.

"debian" branch has been already deleted.
Fix error when 'let' context contains a non-symbol non-list
Merge pull request #711 from berkerpeksag/update-travis

Remove branches configuration from .travis.yml.
Better error messages for fn/defn w/o arglists

When (fn) or (defn) does not get an arglist as first/second parameter,
emit a more descriptive error message, rather than an ugly traceback.

Fixes #716.

Reported-by: Joakim Tall
Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
Merge pull request #717 from algernon/f/defn-better-errors

Better error messages for fn/defn w/o arglists
Added tests for valid/invalid let
Merge remote-tracking branch 'upstream/master'
Better error message for invalid let usage