Fix build with Qt 5.1 development branch

QT_{BEGIN,END}_HEADER defines were removed.
Merge pull request #736 from plfiorini/master

Fix build with Qt 5.1 development branch
Add new option "Ignore system colors" for dark themes.

It will set default background of html element to white.
However, this may break some sites, so let's just make this
optional.
Revert "Add new option "Ignore system colors" for dark themes."

This reverts commit 4b2fd86fdd9da4e16a260d9d09f26152743ffbf2.
Properly fixed page background color with dark themes.

Also fixed building with Qt 4.7
Followup for background fix with dark themes.
Moving translations to Transifex.com

https://www.transifex.com/projects/p/qupzilla
Updated translations.
Added search field in autofill manager in preferences.
WebGL is now enabled by default on QtWebKit 2.3

Also fixed link in README and translated one string in czech
windows installer.
Check for QtWebKit 2.2 availability with pkg-config.

Fixes issues with building with QtWebKit 2.2 and Qt 4.7
Properly export form data if password input is the only input in form.
[autofill] Change saved password when user enters new data.

Closes #734
Fixed matching cookies according RFC 6265.

Perform cookie domain matching on domains without
leading dot.
Matching cookies against blocklist/whitelist is now
also properly working.