Re-license as MIT (#322)

* Closes #317

Author: batpigandme

DESCRIPTION

@@ -20,7 +20,7 @@ Authors@R:
              comment = "Copy of R-project homepage cached as example"))
 Description: Work with XML files using a simple, consistent
     interface. Built on top of the 'libxml2' C library.
-License: GPL (>=2)
+License: MIT + file LICENSE
 URL: https://xml2.r-lib.org/, https://github.com/r-lib/xml2
 BugReports: https://github.com/r-lib/xml2/issues
 Depends:

LICENSE

@@ -0,0 +1,2 @@
+YEAR: 2020
+COPYRIGHT HOLDER: xml2 authors

LICENSE.md

@@ -1,336 +1,21 @@
-GNU General Public License
-==========================
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+# MIT License
+
+Copyright (c) 2020 xml2 authors
+
+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
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+SOFTWARE.

NEWS.md

@@ -1,5 +1,7 @@
 # xml2 (development version)
 
+* xml2 has been re-licensed as MIT (#317).
+
 * `xml_find_all.xml_nodeset()` gains a `flatten` argument to control whether to return a single nodeset or a list of nodesets (#311, @jakejh)
 
 * `write_xml()` and `write_html()` now return NULL invisibly, as they did prior to version 1.3.0 (#307)