SQL parser has quadratic running time when SQL string is very large

SQL parser has quadratic running time when SQL string is very large.

This is due to SimpleCharStream.ExpandBuff(boolean) increasing the buffer in increments of 2,048 (2k) chars. If the SQL string is, say, 1,024k characters, then it will re-alloc at size 2k, 4k, 6k, ..., 1023k, and each time copy the whole string.

This issue was discovered by gian.