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 is separated by comma
- surplus whitespaces will be merged to a single whitespace.
- Use quote to include literal white space in between
e.g.)
e 0,2 hello world
e 4,address 'rhode island'