todo display right padding fix

a long todo item might step on the X sign. `padding-right` of 60 fixes this symmetrically (X sign width 40px, right offset 10).
todo display whitespace fix

currently an item data stored with multiple whitespace in-between words is rendered as having only one space. putting css `white-space: pre` fixes this.
Merge pull request #657 from chenglou/todo-whitespace

todo display whitespace fix
Merge pull request #656 from chenglou/todo-padding

todo display right padding fix