add license and a man page

COPYING

+Copyright (c) 2014, <ale@incal.net>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+

changed.1

+.TH CHANGED 1
+.SH NAME
+changed \- detects whether a file or directory have changed since the
+last invocation
+.SH SYNOPSIS
+.BI "changed [--exclude=" pattern "] [--include=" pattern "] [--db=" path "] [--checksum] " "path ..."
+.SH DESCRIPTION
+.B changed
+detects whether a file or directory tree have changed since the last
+time the tool was invoked with those same arguments. It is primarily
+meant to support configuration management logic, to restart services
+when their configuration has changed.
+
+Arguments can be files or directories: in the latter case,
+.B changed
+will recursively scan the filesystem. You can control the recursion by
+utilizing the
+.I --exclude
+and
+.I --include
+options.
+
+The tool stores its state in the directory specified by the
+.I --db
+option. It will compare the current state of the filesystem with how
+it was the last time
+.B changed
+was invoked with the
+.I exact
+same arguments.
+
+.B changed
+will always report that there have been changes whenever the request
+specification changes subtly, such as if you invoke it with the same
+paths but different
+.I --exclude
+options.
+.SH OPTIONS
+.TP
+.B \-\-checksum
+Use a hash of the file contents for comparisons, rather than relying
+on filesystem attributes (size, modification time). This makes the
+tool noticeably slower, as it has to read all the files, but it is
+appropriate for configurations that are regenerated constantly.
+.TP
+.BI \-\-exclude= pattern
+Exclude files matching
+.I pattern
+from the recursive filesystem scan. This option can be specified
+multiple times. By default,
+.B changed
+excludes backup files and Debian configuration artifacts, but the
+default exclude list can be reset by specifying an empty
+.I pattern
+to this option.
+.TP
+.BI \-\-include= pattern
+Only include files matching
+.I pattern
+in the recursive filesystem scan. This option can be specified
+multiple times. If this option is present, it takes precedence over
+patterns specified with the
+.I --exclude
+option.
+.TP
+.BI \-\-db= path
+Store checksums in the directory specified by
+.I path
+(by default this is /var/lib/changed if the current user has uid 0,
+$HOME/.changed otherwise).
+.SH "EXIT STATUS"
+.B changed
+will exit with status 0 if the specified files have changed (or if no
+previous state was found), or 1 if they have not. This makes it
+possible to use it with relatively intuitive semantics:
+.PP
+.nf
+.RS
+if changed /etc/foo; then restart-foo; fi
+.RE
+.fi
+.PP
+.SH AUTHOR
+Ale <ale at incal dot net>
+.SH BUGS
+Plenty, but still unknown.