Xs dancer core request

[celogeek]

I have add improvement on Dancer::Core::Request.

If URL::Encode::XS is installed, it will use it instead of pure perl _url_encode
To parse the params I check if CGI::Deurl::XS is present, and I use parse_query_string from it.

Both is a a lot of faster than pure perl version.

I have made a speed test to compare,

pure perl (master branch): 3472 Dancer::Core::Request->new per second
with XS (my branch) : 3900 Dancer::Core::Request->new per second

I have add a comment in the request for extra speed, and add a diag in the request.t to tell people to install them for extra speed.

It is not a dependencies, but it speed up dancer if they are present.

[bigpresh]

Looks pretty clean & sane, and the speed boost is nice.

I'm mildly wary in case the XS versions differ from the pure-Perl versions at all in any way (now or in the future) which could cause odd side effects / hard to track bugs, though. Perhaps we could add a test which, if the XS modules are detected, compares the result of CGI::Deurl::XS::parse_query_string() and URL::Encode::XS::url_decode() against the pure-Perl equivalents, so that if the behaviour begins to differ at any point, we'll find out.

So, cautious approval here.

[celogeek]

You are right. I was thinking of doing the request test twice, one with and one without the XS module if present.
I will work on it.

[celogeek]

I have rebase the code on the latest master to permit an easy merge.