move the library files in a separate folder + misc changes

- dont do such commits at home

library/src/main/kotlin/com/simplemobiletools/filepicker/models/FileDirItem.kt

@@ -0,0 +1,19 @@
+package com.simplemobiletools.filepicker.models
+
+class FileDirItem(val path: String, val name: String, val isDirectory: Boolean, val children: Int, val size: Long) :
+        Comparable<FileDirItem> {
+
+    override fun compareTo(other: FileDirItem): Int {
+        if (isDirectory && !other.isDirectory) {
+            return -1
+        } else if (!isDirectory && other.isDirectory) {
+            return 1
+        }
+
+        return name.toLowerCase().compareTo(other.name.toLowerCase())
+    }
+
+    override fun toString(): String {
+        return "FileDirItem{name=$name, isDirectory=$isDirectory, path=$path, children=$children, size=$size}"
+    }
+}