Incorporate the changes of other two PRs scalamacros#6 and scalamacros#7

Author: dj707chen

UNLICENCE

@@ -0,0 +1,24 @@
+This is free and unencumbered software released into the public domain.
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+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 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.
+
+For more information, please refer to <http://unlicense.org/>

build.sbt

@@ -1,17 +1,14 @@
 name := "sbt-example"
 organization := "org.scalamacros"
-version := "2.0.1"
+version := "2.0.0"
 
-ThisBuild / scalaVersion := "2.13.14"
+ThisBuild / crossScalaVersions := Seq("2.13.14", "2.12.19", "2.11.12")
+ThisBuild / scalaVersion := crossScalaVersions.value.head
 
-// this line is not valid in Scala 2.13 due to <<=, migrate according to https://www.scala-sbt.org/0.13/docs/Migrating-from-sbt-012x.html
-//run <<= run in Compile in core
+run := (core / Compile / run).evaluated
 
-// alias is the way to go, now you can do: sbt runMy
-addCommandAlias("runMy", "core / Compile / run")
-
-lazy val macros = (project in file("macros")).settings(
+lazy val macros = project in file("macros") settings(
  libraryDependencies += "org.scala-lang" % "scala-reflect" % scalaVersion.value
 )
 
-lazy val core = (project in file("core")) dependsOn macros
+lazy val core = project in file("core") dependsOn macros