add a license

Based on a 3-clause BSD license allowing use and modification in
source forms, and use in binary form, but explicitly forbidding
redistribution in binary form.

This should not negatively affect anyone's personal use of this code
unless you're trying to rip me off by changing the name and icon and
sticking it on the App Store for $1.99.

LICENSE

@@ -0,0 +1,33 @@
+endless
+Copyright (c) 2014 joshua stein <jcs@jcs.org>
+
+(NOTE: This is not a BSD/ISC/MIT license.  You are permitted to use this
+source code, with or without modification, in source or binary form, on
+your devices however you see fit.  You are not permitted to redistribute
+binaries of this source code, with or without modification.  In other
+words, you cannot put this application or any application derived from
+it, on the Apple App Store, Cydia, or any other binary-only distribution
+channel.)
+
+Redistribution and use in source form, with or without modification,
+and use in binary form, is permitted provided that the following conditions
+are met:
+
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+2. The name of the author may not be used to endorse or promote products
+   derived from this software without specific prior written permission.
+
+Redistribution in binary form, with or without modification, is not
+permitted.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.