Change licence to MIT

Closes #1063

.Rbuildignore

@@ -15,3 +15,4 @@
 ^\.github$
 .*\.dir-locals\.el$
 ^\.github/workflows/R-CMD-check\.yaml$
+^LICENSE\.md$

DESCRIPTION

@@ -9,7 +9,7 @@ Authors@R: c(
     person("Hadley", "Wickham", ,"hadley@rstudio.com", "aut"),
     person("RStudio", role = "cph")
     )
-License: GPL-3
+License: MIT + file LICENSE
 LazyData: true
 ByteCompile: true
 Biarch: true

LICENSE

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

LICENSE.md

@@ -0,0 +1,21 @@
+# MIT License
+
+Copyright (c) 2020 rlang 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
+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.

NEWS.md

@@ -1,5 +1,7 @@
 # rlang (development version)
 
+* rlang is now licensed as MIT (#1063).
+
 * Fixed an issue causing extra empty lines in `inform()` messages with
   `.frequency` (#1076, @schloerke).