trivial-features ensures consistent *FEATURES* across multiple Common
Lisp implementations.

For example, on MacOS X platforms, while most Lisps push :DARWIN to
*FEATURES*, CLISP and Allegro push :MACOS and :MACOSX instead,
respectively.  Some Lisps might not push any feature suggesting MacOS
X at all.  trivial-features will make sure all Lisps will have :DARWIN
in the *FEATURES* list when running on MacOS X.  This way, you can
write

   #+darwin foo #-darwin bar

instead of

   #+(or darwin macos macosx) foo
   #-(or darwin macos macosx) bar

The included SPEC document describes the set of symbols that should or
should not be present in CL:*FEATURES* on certain circumstances.  This
specification is implemented by the TRIVIAL-FEATURES system which
supports a handful of Lisps.

The test suite is, in effect, an implementation using CFFI that is
checked against the various implementations in src/tf-*.lisp.

trivial-features is MIT-licenced.