Fallback to non-skeleton Header (Juanpe#416)

Sometimes my collectionview's header doesn't need to be 'skeletoned' while the content does.  

When  collectionSkeletonView(_ skeletonView: UICollectionView, supplementaryViewIdentifierOfKind: String, at indexPath: IndexPath) -> ReusableCellIdentifier? returns nil, it's best if we fallback to the non-skeleton header.

Fixed background color warning in `UITableViewHeaderFooterView` (Juan…

…pe#417)

Add `prepareCellForSkeleton` for `UITableView` and `UICollectionView` (…

…Juanpe#415)

* Add prepareCellForSkeleton for UITableView and UICollectionView

* Update README to add collectionSkeletonView(_ skeletonView: UICollectionView, prepareCellForSkeleton cell: UICollectionViewCell, at indexPath: IndexPath)

* Update README.md

Co-authored-by: Juanpe Catalán <juanpecm@gmail.com>

Delay the presentation of the skeletons (Juanpe#411)

Replace SkeletonCollectionDataSource.automaticNumberOfRows with UITab…

…leView.automaticNumberOfSkeletonRows and UICollectionView.automaticNumberOfSkeletonItems (Juanpe#409)

fix typo `isUserInteractionDisabledWhenSkeletonIsActive` (Juanpe#404)

* fix typo

* update README

update README file

use the right delegate method for footers (Juanpe#394)

[BUG] Fix crashing on NaN value (Juanpe#382)

UnSwizzle methods when SkeletonView is hidden (Juanpe#381)

* Add InputAccessoryView to textField

* Add method to removeOnce Add unSwizzleMethods that are called when recursiveHideSkeleton

Co-authored-by: Alexandros Lykesas <alexandros.lykesas@untis.at>