cleanup license file (no functional change)

With permission from Tom Hawkins, I have updated sv2v's existing BSD
3-Clause license to match the exact text of the standard BSD 3-Clause
license. The wording changes, listed below in full, are entirely
innocuous. The copyright attribution is now simpler. The license heading
and link have been removed from the readme. These changes enable the
license to be appropriately detected by GitHub's license detection tool,
hopefully eliminating any potential confusion about the license in use.

- "author" ==> "copyright holder"
- "his" ==> "its"
- "AUTHORS" ==> "COPYRIGHT HOLDERS AND CONTRIBUTORS"
- "AUTHORS" ==> "COPYRIGHT HOLDER"

LICENSE

 BSD 3-Clause License
 
-Copyright for portions of sv2v are held by Tom Hawkins, 2011-2015, as part of
-tomahawkins/verilog. Copyright for all other portions of sv2v are held by
-Zachary Snow, 2019-2021.
+Copyright 2019-2021 Zachary Snow
+Copyright 2011-2015 Tom Hawkins
 
 All rights reserved.
 
@@ -16,17 +15,17 @@ are permitted provided that the following conditions are met:
    this list of conditions and the following disclaimer in the documentation
    and/or other materials provided with the distribution.
 
-3. Neither the name of the author nor the names of his contributors may be used
-   to endorse or promote products derived from this software without specific
-   prior written permission.
+3. Neither the name of the copyright holder nor the names of its contributors
+   may be used to endorse or promote products derived from this software without
+   specific prior written permission.
 
-THIS SOFTWARE IS PROVIDED BY THE AUTHORS "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 AUTHORS OR CONTRIBUTORS 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.
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR CONTRIBUTORS 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.

README.md

@@ -159,8 +159,3 @@ no prior experience, and has also helped with test cases.
 Since sv2v's public release, several people have taken the time to file detailed
 bug reports and feature requests. I greatly appreciate their help in furthering
 the project.
-
-
-## License
-
-See the [LICENSE file](LICENSE) for copyright and licensing information.