Update license to Apache 2.0 or MIT, copyright to Bitcoin Dev Kit Developers

LICENSE

@@ -1,21 +1,14 @@
-MIT License
+This software is licensed under [Apache 2.0](LICENSE-APACHE) or
+[MIT](LICENSE-MIT), at your option.
 
-Copyright (c) 2020 Magical Bitcoin
+Some files retain their own copyright notice, however, for full authorship
+information, see version control history.
 
-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:
+Except as otherwise noted in individual files, all files in this repository are
+licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+http://www.apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
+http://opensource.org/licenses/MIT>, at your option.
 
-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.
+You may not use, copy, modify, merge, publish, distribute, sublicense, and/or
+sell copies of this software or any files in this repository except in
+accordance with one or both of these licenses.