[perf] 性能优化，SectionInfo的end作为属性，因为contains调用相对频繁，不用每次判断contains都做加法

Author: xiangning17

library/src/main/java/com/xiangning/sectionadapter/core/SectionInfo.kt

@@ -3,13 +3,24 @@ package com.xiangning.sectionadapter.core
 /**
  * 分组信息封装
  */
-data class SectionInfo<T>
+class SectionInfo<T>
 @JvmOverloads
-constructor(val section: T, var start: Int, var count: Int = 0) {
-    val end: Int
-        get() = start + count
+constructor(val section: T, start: Int, count: Int = 0) {
+    var start: Int = start
+        set(value) {
+            end += value - start
+            field = value
+        }
+    var end: Int = start + count
+        private set
 
-    operator fun contains(fullPos: Int): Boolean = fullPos in start until start + count
+    var count: Int
+        get() = end - start
+        set(value) {
+            end = start + value
+        }
+
+    operator fun contains(fullPos: Int): Boolean = fullPos in start until end
 
     fun toSectionPos(fullPos: Int) = fullPos - start
     fun toFullPosition(sectionPos: Int) = start + sectionPos

library/src/main/java/com/xiangning/sectionadapter/core/SectionListCounter.kt

@@ -13,7 +13,7 @@ class SectionListCounter<T : Any> {
 
     private val hitInfo = HitInfo<T>()
 
-    private val indexes = LinkedHashMap<T, Int>()
+    private val indexes = HashMap<T, Int>()
     private val sectionInfoList = mutableListOf<SectionInfo<T>>()
 
     @JvmOverloads