在windows上執行composer update，用到了intervention/image這個包，執行過程中提示推薦安裝兩個包：

intervention/image suggests installing ext-imagick (to use Imagick based image p                                                                              rocessing.)
intervention/image suggests installing intervention/imagecache (Caching extensio                                                                              n for the Intervention Image library)

關於這兩個包有3個疑問：
1、兩個包分別是做什麼的？
2、第1個套件在github上找不到，那麼在哪裡下載？
3、第2個包可以在github上找到，但好久沒更新了，過時了沒有？

附：指令執行時完整資訊：

dell@DESKTOP-MVU77SM MINGW64 /d/wnmp/www/laravel-5-3-demo
$ composer update
Loading composer repositories with package information
Updating dependencies (including require-dev)
  - Installing psr/http-message (1.0.1)
    Downloading: 100%

  - Installing guzzlehttp/psr7 (1.3.1)
    Downloading: 100%

  - Installing intervention/image (dev-master 6886d43)
    Downloading: 100%

  - Installing laravelcollective/html (dev-master c4c8791)
    Downloading: 100%

  - Installing adambrett/shell-wrapper (dev-master d1fb1a6)
    Downloading: 100%

  - Removing laravel/framework (5.3.x-dev bd9cd77)
  - Installing laravel/framework (5.3.x-dev 12336ad)
    Downloading: 100%

intervention/image suggests installing ext-imagick (to use Imagick based image p                                                                              rocessing.)
intervention/image suggests installing intervention/imagecache (Caching extensio                                                                              n for the Intervention Image library)
Writing lock file
Generating autoload files
> Illuminate\Foundation\ComposerScripts::postUpdate
> php artisan optimize
Generating optimized class loader