Add 96x96 image size for avatar thumbnails

[benlk]

Largo defines a lot of image sizes:

https://github.com/INN/largo/blob/17caa1eadcc889b19af8047d6369428fce8e7823/functions.php#L253-L261

But it doesn't define the one that we use in a lot of places for thumbnails:

https://github.com/INN/largo/blob/7e7b4cd65105c5dab3d5ea9f6dc4bce957d2a7e0/partials/author-bio-description.php#L14-L20

96px x 96px is the default size used by the function get_avatar(), and the size used by Largo's author bio widget, but that 96x96 size is not registered by default in WordPress or in Largo. Here's the list of image sizes in Largo that are registered as of the current 0.5-dev:

var_dump( $_wp_additional_image_sizes, true)
array(8) {
  ["post-thumbnail"]=>
  array(3) {
    ["width"]=>    int(140)
    ["height"]=>    int(140)
    ["crop"]=>    bool(true)
  }
  ["60x60"]=>
  array(3) {
    ["width"]=>    int(60)
    ["height"]=>    int(60)
    ["crop"]=>    bool(true)
  }
  ["medium"]=>
  array(3) {
    ["width"]=>    int(336)
    ["height"]=>    int(9999)
    ["crop"]=>    bool(false)
  }
  ["large"]=>
  array(3) {
    ["width"]=>    int(771)
    ["height"]=>    int(9999)
    ["crop"]=>    bool(false)
  }
  ["full"]=>
  array(3) {
    ["width"]=>    int(1170)
    ["height"]=>    int(9999)
    ["crop"]=>    bool(false)
  }
  ["third-full"]=>
  array(3) {
    ["width"]=>    int(390)
    ["height"]=>    int(500)
    ["crop"]=>    bool(true)
  }
  ["two-third-full"]=>
  array(3) {
    ["width"]=>    int(780)
    ["height"]=>    int(500)
    ["crop"]=>    bool(true)
  }
  ["rect_thumb"]=>
  array(3) {
    ["width"]=>    int(800)
    ["height"]=>    int(600)
    ["crop"]=>    bool(true)
  }
}

Fix:

• add_image_size( '96x96', 96, 96, true );
• add note to changelog that this will require regenerating thumbnails (recommend a plugin) or re-uploading avatars.

Largo does define the thumbnail image size to be 140x140, though, so we may be able to add image srcsets to get_avatar via wp_get_attachment_image_srcset as an argument onget_avatar as the fifth parameter array( 'extra_args' => '...' ) but that seems very extra, and only worth implementing as part of a comprehensive srcset review in #1577

[benlk]

If the image size changes in Largo from96x96, update https://github.com/INN/umbrella-wcij/blob/c33d1d07c4ec938b2bc44bd07da77b57251d3de9/wp-content/themes/wisconsinwatch/partials/author-bio-description.php#L46-L52

[benlk]

Historical note: https://secure.helpscout.net/conversation/760717711/3100/?folderId=1211656