[RMMV-MZ] Random Loot

 * ***************** Description **********************
 * Script Calls:
 *   $gameParty.gainRandomLoot([start], [max], [data], [howMany])
 *   $gameParty.gainRandomItem(start, max, howMany)
 *   $gameParty.gainRandomWeapon(start, max, howMany)
 *   $gameParty.gainRandomArmor(start, max, howMany)
 *
 * Examples:
 *   $gameParty.gainRandomLoot([start], [max], [data], [howMany])
 *    ex. $gameParty.gainRandomLoot() // This will give a random item from the entire Item database
 *        $gameParty.gainRandomLoot(31, 20, $dataWeapons, 2) // This will 2 a a random weapon of an ID 31 to 51
 *        $gameParty.gainRandomLoot(14, 3, null, 10) // This is the same as the below
 *    $gameParty.gainRandomLoot(14, 3, $dataItems, 10) // This will 10 a a random items of an ID 14 to 17
 * 
 *  $gameParty.gainRandomItem(start, max, howMany)
 *    ex. $gameParty.gainRandomItem() // This will give a random item from the entire Item database
 *    $gameParty.gainRandomItem(31, 20) // This will 1 a a random items of an ID 31 to 51
 *    $gameParty.gainRandomItem(31, 20,  2) // This will 2 a a random items of an ID 31 to 51
 *    $gameParty.gainRandomItem(14,  3, 10) // This will 10 a a random items of an ID 14 to 17
 *
 *   $gameParty.gainRandomWeapon(start, max, howMany)
 *     ex. $gameParty.gainRandomWeapon() // This will give a random item from the entire Item database
 *    $gameParty.gainRandomWeapon(31, 20) // This will 1 a a random items of an ID 31 to 51
 *    $gameParty.gainRandomWeapon(31, 20,  2) // This will 2 a a random items of an ID 31 to 51
 *    $gameParty.gainRandomWeapon(14,  3, 10) // This will 10 a a random items of an ID 14 to 17 
 *
 *   $gameParty.gainRandomArmor(start, max, howMany)
 *    ex. $gameParty.gainRandomArmor() // This will give a random item from the entire Item database
 *    $gameParty.gainRandomArmor(31, 20) // This will 1 a a random items of an ID 31 to 51
 *    $gameParty.gainRandomArmor(31, 20,  2) // This will 2 a a random items of an ID 31 to 51
 *    $gameParty.gainRandomArmor(14,  3, 10) // This will 10 a a random items of an ID 14 to 17
 *
 *  More examples:
 *    Set Game Variable #1 to the name of last random item reveived:
 *      $gameVariables.setValue(1, $gameParty._lastRandomLoot.name)
 *    Set Game Variable #1 to the last random item choices (raw data):
 *      $gameVariables.setValue(1, $gameParty._lastRandomLootChoices)