Changing the defaults for HTTP ACCEPT, ACCEPT-LANGUAGE and USERAGENT headers

[Dawit A]

In hopes of making Konqueror's default settings for the aforementioned
HTTP headers inline with other browsers, I want to change the default
settings for these three header as outlined below.

** Please note that this only affects the default! Each and every
application can tell the ioslave what to use through the KIO meta-data
system for each one of these parameters.

USER-AGENT HEADER
=================
OLD DEFAULT:  Mozilla/5.0 (compatible; Konqueror/4.6; Linux)
KHTML/4.6.41 (like Gecko)
NEW DEFAULT: Mozilla/5.0 (X11) KHTML/4.6.41 (like Gecko) Konqueror/4.6

OLD Full:    Mozilla/5.0 (compatible; Konqueror/4.6; Linux 2.6.31;
x86-64; en_US) KHTML/4.6.41 (like Gecko)
NEW Full:   Mozilla/5.0 (X11; Linux 2.6.31 x86-64; en_US) KHTML/4.6.41
(like Gecko) Konqueror/4.6


Changes:
--------------
- Drop the "U" letter which is a vestige left from the early days of
Mozilla to denote strong security support. Since all browsers now days
automatically come with support for this functionality, there is no
need for such letter. Instead only a "N" will be added when a browser
is compiled without support for encrypted communication.

- Drop the word "compatible" from the string since it is really
useless. I would like to drop the "like Gecko" text as well, but I
have no idea what kind of impact that would have on khtml so I opted
to leave it alone.

- Other than the above to the only change is to move around the order
of what is inside the "( )".

ACCEPT HEADER:
==============
OLD: text/html, image/jpeg;q=0.9, image/png;q=0.9, text/*;q=0.9,
image/*;q=0.9, */*;q=0.8
NEW: text/html, application/xhtml+xml, application/xml;q=0.9, */*;q=0.8

Changes:
-------------
- Again this is intended to make the default inline with what Firefox
and to a large degree Chrome send. Since */*; it is pointless to list
the other preferences we have. Specially when it comes to images since
Qt supports a lot of other image formats not listed here equally well.

Only question is whether or not sending anything that has "/xml" in it
detrimental to khtml ? Just as an FYI, by default, QtWebKit sends this
same header (the firefox version).

ACCEPT LANGUAGE HEADER:
========================
OLD: utf-8, utf-8;q=0.5, *;q=0.5  (see the duplicate ??)
NEW: utf-8, *;q=0.5

Changes:
-------------
This is a fix more than a change. Currently the language header
duplicates the utf8 entry by appending the default onto whatever the
application specified. The fix is to change the code to not do that.
Instead it will simply append the default *;q=0.5 if it is missing
from the charset value defined by the application.

Input, suggestion, objections are welcome...

Regards,
Dawit A.