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/psi/examples/util/Comparison.kt

@@ -5,7 +5,7 @@ fun naturalOrder<in T : Comparable<T>>(a : T, b : T) : Int = a.compareTo(b)
 fun castingNaturalOrder(a : Object, b : Object) : Int = (a as Comparable<Object>).compareTo(b as Comparable<Object>)
 
 enum class ComparisonResult {
-  LS; EQ; GR
+  LS, EQ, GR;
 }
 
 typealias MatchableComparison<in T> =  (T, T) -> ComparisonResult

compiler/testData/psi/examples/util/Comparison.txt

@@ -217,16 +217,17 @@ JetFile: Comparison.kt
       ENUM_ENTRY
         OBJECT_DECLARATION_NAME
           PsiElement(IDENTIFIER)('LS')
-        PsiElement(SEMICOLON)(';')
+      PsiElement(COMMA)(',')
       PsiWhiteSpace(' ')
       ENUM_ENTRY
         OBJECT_DECLARATION_NAME
           PsiElement(IDENTIFIER)('EQ')
-        PsiElement(SEMICOLON)(';')
+      PsiElement(COMMA)(',')
       PsiWhiteSpace(' ')
       ENUM_ENTRY
         OBJECT_DECLARATION_NAME
           PsiElement(IDENTIFIER)('GR')
+      PsiElement(SEMICOLON)(';')
       PsiWhiteSpace('\n')
       PsiElement(RBRACE)('}')
   PsiWhiteSpace('\n\n')