added heading
animations checkbox made smaller
added rounding to resetItemsHeight()
refactoring setItemHeight()
added more space on the top and bottom of page
addded note to TODO list
intervals smaller than 90 will be more visually distinguished between each other (e.g.: difference between 30 and 60 min will be bigger than 330 and 360) while keeping the height in boundaries set by minItemHeight and maxItemHeight
added item to TODO list
refactoring + coments