Add "update-release" target to merge dev branches to release

makefile.shade

@@ -111,6 +111,27 @@ functions
         }
     }
 
+#update-release
+    -// Merge dev branch to release
+    @{
+        foreach (var repo in GetAllRepos())
+        {
+            CloneOrUpdate(repo);
+            try
+            {
+                GitCommand(repo, "checkout release");
+            }
+            catch
+            {
+                // If the release branch does not exist, create a new branch and reset origin/dev to it.
+                GitCommand(repo, "checkout origin/dev -b release");
+            }
+
+            GitCommand(repo, "merge origin/dev");
+            GitCommand(repo, "push origin release");
+        }
+    }
+
 #reset-master
     -// Resets master branch to release
     for each='var repo in GetAllRepos()'
@@ -227,6 +248,9 @@ macro name='GitStatus' gitFolder='string'
 macro name='GitClean' gitFolder='string'
     git gitCommand='clean -xdf'
 
+macro name='GitCommand' gitFolder='string' gitCommand='string'
+    git
+
 macro name='Exec' program='string' commandline='string' workingdir='string'
     exec