New enum syntax: Short constructor syntax introduced for entries, optional commas between entries, semicolon after entries. #KT-7605 Fixed.

Grammar changed accordingly.
Semicolons prohibited after an entry except the last one.
Only one initializer is allowed per entry.
EnumReferenceExpression AST node introduced.
Some tests fixed, a pair of new tests written. Kotlin code inside project fixed.
Formatter and intendation tests fixed accordingly.
Stub version is incremented.

compiler/testData/codegen/box/enum/enumShort.kt

@@ -0,0 +1,11 @@
+enum class Color(val rgb: Int) {
+    RED(0xff0000),
+    GREEN(0x00ff00),
+    BLUE(0x0000ff);
+}
+
+fun foo(): Int {
+    return Color.RED.rgb + Color.GREEN.rgb + Color.BLUE.rgb
+}
+
+fun box() = if (foo() == 0xffffff) "OK" else "Fail: ${foo()}"