Prepare for 3.1.0 release

DAFFODIL-2514
diff --git a/build.sbt b/build.sbt
index 40854f3..0fda81e 100644
--- a/build.sbt
+++ b/build.sbt
@@ -148,7 +148,7 @@
 
 lazy val commonSettings = Seq(
   organization := "org.apache.daffodil",
-  version := "3.1.0-SNAPSHOT",
+  version := "3.1.0",
   scalaVersion := "2.12.13",
   crossScalaVersions := Seq("2.12.13"),
   scalacOptions ++= Seq(
diff --git a/daffodil-runtime2/src/test/resources/org/apache/daffodil/runtime2/examples/NestedUnion/generated_code.c b/daffodil-runtime2/src/test/resources/org/apache/daffodil/runtime2/examples/NestedUnion/generated_code.c
index ab71748..833f045 100644
--- a/daffodil-runtime2/src/test/resources/org/apache/daffodil/runtime2/examples/NestedUnion/generated_code.c
+++ b/daffodil-runtime2/src/test/resources/org/apache/daffodil/runtime2/examples/NestedUnion/generated_code.c
@@ -8,7 +8,7 @@
 
 // Initialize our program's name and version
 
-const char *daffodil_program_version = "daffodil-runtime2 3.1.0-SNAPSHOT";
+const char *daffodil_program_version = "daffodil-runtime2 3.1.0";
 
 // Declare prototypes for easier compilation
 
diff --git a/daffodil-runtime2/src/test/resources/org/apache/daffodil/runtime2/examples/ex_nums/generated_code.c b/daffodil-runtime2/src/test/resources/org/apache/daffodil/runtime2/examples/ex_nums/generated_code.c
index 02df28a..e9445de 100644
--- a/daffodil-runtime2/src/test/resources/org/apache/daffodil/runtime2/examples/ex_nums/generated_code.c
+++ b/daffodil-runtime2/src/test/resources/org/apache/daffodil/runtime2/examples/ex_nums/generated_code.c
@@ -8,7 +8,7 @@
 
 // Initialize our program's name and version
 
-const char *daffodil_program_version = "daffodil-runtime2 3.1.0-SNAPSHOT";
+const char *daffodil_program_version = "daffodil-runtime2 3.1.0";
 
 // Declare prototypes for easier compilation