KT-3715 make Collection.notEmpty a property

Renamed "notEmpty()" methods to "isNotEmpty()" in following classes:
    - Collection
    - String
    - Array

Added "notEmpty" property to Collection class

libraries/stdlib/src/kotlin/Arrays.kt

@@ -1,7 +1,7 @@
 package kotlin
 
 /** Returns true if the array is not empty */
-public inline fun <T> Array<T>.notEmpty() : Boolean = !this.isEmpty()
+public inline fun <T> Array<T>.isNotEmpty() : Boolean = !this.isEmpty()
 
 /** Returns true if the array is empty */
 public inline fun <T> Array<T>.isEmpty() : Boolean = this.size == 0

libraries/stdlib/src/kotlin/JUtil.kt

@@ -17,7 +17,11 @@ val Int.indices: IntRange
     get() = 0..this-1
 
 /** Returns true if the collection is not empty */
-public inline fun <T> Collection<T>.notEmpty() : Boolean = !this.isEmpty()
+public inline fun <T> Collection<T>.isNotEmpty() : Boolean = !this.isEmpty()
+
+/** Returns true if this collection is empty */
+val Collection<*>.notEmpty : Boolean
+    get() = isNotEmpty()
 
 /** Returns the Collection if its not null otherwise it returns the empty list */
 public inline fun <T> Collection<T>?.orEmpty() : Collection<T>

libraries/stdlib/src/kotlin/Strings.kt

@@ -30,7 +30,7 @@ public inline fun String.trimTrailing(postfix: String): String {
 }
 
 /** Returns true if the string is not null and not empty */
-public inline fun String?.notEmpty() : Boolean = this != null && this.length() > 0
+public inline fun String?.isNotEmpty() : Boolean = this != null && this.length() > 0
 
 /**
 Iterator for characters of given CharSequence

libraries/stdlib/src/kotlin/StringsJVM.kt

@@ -179,7 +179,7 @@ get() = length()
  * @includeFunctionBody ../../test/StringTest.kt capitalize
  */
 public inline fun String.capitalize(): String {
-    return if (notEmpty() && charAt(0).isLowerCase()) substring(0, 1).toUpperCase() + substring(1) else this
+    return if (isNotEmpty() && charAt(0).isLowerCase()) substring(0, 1).toUpperCase() + substring(1) else this
 }
 
 /**
@@ -188,7 +188,7 @@ public inline fun String.capitalize(): String {
  * @includeFunctionBody ../../test/StringTest.kt decapitalize
  */
 public inline fun String.decapitalize(): String {
-    return if (notEmpty() && charAt(0).isUpperCase()) substring(0, 1).toLowerCase() + substring(1) else this
+    return if (isNotEmpty() && charAt(0).isUpperCase()) substring(0, 1).toLowerCase() + substring(1) else this
 }
 
 /**