[Development] QTBUG-23489: Implement the new regular expression classes using PCRE

[lars.knoll at nokia.com]

Hi,

this is the first mail where I'd like to go through the remaining features
for Qt 5.0.

I know that this bug is blocked by not having PCRE in 3rdparty/. But how
is the status apart from this? Thiago, simply tell me if you feel
comfortable with the code and I'll do final review and approval. If it
doesn't break BC and is standalone from other code in qtcore, it can go
into master, otherwise I'd prefer it to go into api_changes.

There's another related issue to this bug: What do we do with the old
QRegExp? I've gripped through our code and removing it is a larger
surgical operation.

So I'd propose that we now bite the bullet and leave it in QtCore. Let's
simply mark it as deprecated since 5.0, and live with the additional 100k
in QtCore.

Cheers,
Lars