Options for blank lines between 'when' branches

#KT-18607 Fixed

idea/testData/formatter/WhenBlockBlankLines.after.kt

@@ -0,0 +1,13 @@
+fun f(x: Int) = when (x) {
+    1 -> "Foo"
+    2 -> "Bar"
+
+    3 -> {
+        "Foo"
+    }
+
+    4 -> "Bar"
+    else -> "Xyzzy"
+}
+
+// SET_INT: BLANK_LINES_AROUND_BLOCK_WHEN_BRANCHES = 1

idea/testData/formatter/WhenBlockBlankLines.kt

@@ -0,0 +1,11 @@
+fun f(x: Int) = when(x) {
+    1 -> "Foo"
+    2 -> "Bar"
+    3 -> {
+        "Foo"
+    }
+    4 -> "Bar"
+    else -> "Xyzzy"
+}
+
+// SET_INT: BLANK_LINES_AROUND_BLOCK_WHEN_BRANCHES = 1

idea/testData/formatter/WhenEntryExpr.after.kt

@@ -57,4 +57,4 @@ fun some(x: Any) {
             1
         }
     }
-}
+}

idea/testData/formatter/WhenEntryExpr.kt

@@ -65,4 +65,4 @@ else
 1
 }
 }
-}
+}