edit, e <COORDINATE: (usize,usize)> <VALUE: string>
	Edit a cell with given coordinate and value. Second argument can also be a
	name of the column.

	**Syntax Caveat**
	- Coordinate should not have a whitesapce in between.
	- surplus whitespaces will be merged to a single whitespace.

	e.g.)
		e 0,2 hello world
		e 4,address rhode island

