deleteColumn method
Removes the column with given index.
The index must be in the range 0..columns-1.
Implementation
void deleteColumn(int index) {
if (index >= columns || index < 0) {
throw ArgumentError('index must be a valid column index');
}
for (var row in _table) {
row.removeAt(index);
}
_columnAlignments.removeAt(index);
_columnWidths.removeAt(index);
assert(_tableIntegrity);
}