specfile
property debug
[storage] remove filePath argument from StoragePlugin::eventGenerated()

Not used anywhere.
[storage] move FSStoragePlugin::getObjectFormatByExtension() to StorageItem

Some methods that are now in FSStoragePlugin logically rather belong to
StorageItem class, which was so far treated just as a simple data
container. Moving them will help to make the code better arranged and
simplify the convoluted storage plugin class.

This is the first in likely larger set of commits that split
responsibilities between FSStoragePlugin and StorageItem.
[storage] move FSStoragePlugin::getObjectSize() to StorageItem
bordel
[storage] move FSStoragePlugin::isImage() to StorageItem

Improved by utilizing existing code.
[storage] removed FSStoragePlugin::getThumbFormat()

No reason for this to be a method.
[storage] remove getThumbPixelWidth() and getThumbPixelHeight()
[storage] remove getImagePixelWidth() and getImagePixelHeight()
[storage] remove FSStoragePlugin::getImageBitDepth()
[storage] move FSStoragePlugin::getAssociationType() to StorageItem
[storage] removed FSStoragePlugin::getAssociationDescription()
[storage] remove FSStoragePlugin::getSequenceNumber()
[storage] remove FSStoragePlugin::getMTPProtectionStatus()
[storage] move FSStoragePlugin::getCreatedDate() into StorageItem
[storage] move FSStoragePlugin::getModifiedDate() into StorageItem
[storage] remove FSStoragePlugin::getKeywords()
[thumbnailer] make Thumbnailer a singleton
[storage] Add StorageItem::thumbnailPath()

Hides away most of the thumbnail creation handling from FSStoragePlugin.
The plugin still has to connect to Thumbnailer::thumbnailReady() and
update the storage item in receiveThumbnail(). This will change in the
future.