regexp_replace

I made the patch that implements regexp_replace again.
The specification of this function is as follows.

regexp_replace(source text, pattern text, replacement text, [flags text])
returns text

Replace string that matches to regular expression in source text to
replacement text.

- pattern is regular expression pattern.
- replacement is replace string that can use '\1'-'\9', and '\&'.
'\1'-'\9': back reference to the n'th subexpression.
'\&' : entire matched string.
- flags can use the following values:
g: global (replace all)
i: ignore case
When the flags is not specified, case sensitive, replace the first
instance only.

regards,

--- Atsushi Ogawa