allow Item to has children
delete exam_preparation
initial exam commit
add sample images
add constructors
remove render method
add ImageList and AlbumList
implement nesting an Album inside another Album
make Album collapsible
add gallery storage scaffold
serialize Gallery to JSON
build Gallery from repository data
zoom an image on click
sort albums
get dimensions from already rendered img element
Revert "delete exam_preparation"

This reverts commit 4203d7d7a1d86519ddad60343b6f9764aa792460.