trim whitespace when casting from string

[jycor]

MySQL will trim leading and trailing space(' ') and tab ('\t') characters when casting from a string to a numeric type.

mysql> select cast('\t    123   \t\t' as signed);
+------------------------------------+
| cast('\t    123   \t\t' as signed) |
+------------------------------------+
|                                123 |
+------------------------------------+
1 row in set (0.0004 sec)

Oddly, MySQL will not trim NUL ('\0') or new line ('\n') characters.

mysql> select cast('\0123' as signed);
+-------------------------+
| cast('\0123' as signed) |
+-------------------------+
|                       0 |
+-------------------------+
1 row in set, 1 warning (0.0004 sec)
Warning (code 1292): Truncated incorrect INTEGER value: ''

mysql> select cast('\n123' as signed);
+-------------------------+
| cast('\n123' as signed) |
+-------------------------+
|                       0 |
+-------------------------+
1 row in set, 1 warning (0.0004 sec)
Warning (code 1292): Truncated incorrect INTEGER value: '
123'

Currently, dolt does not trim any of these.