#Thumbnail displays a small sized image
default width: app.sizes.xxxLarge * 3
default height: app.sizes.xxxLarge * 3
default fillMode: Image.PreserveAspectFit
###Example
Thumbnail {
id: thumb
picture: uploadThumbnail.picture
fillMode: Image.Stretch
onClicked: console.log("Thumbnail clicked")
}
##Properties
###marker: string This property holds a number or a string to be displayed if no image loaded
###picture: string This property holds the path of the image to be displayed
##Signals
###clicked
This signal will be emitted when Thumbnail
is clicked