[Qt5] Fixed building with Qt5.
[Qt5] Fixed failing FormCompleter tests.
[Windows] Linking to system hunspell library
[Windows] Adjust height of AboutDialog.
Faster 'filterString()' for CookieManager.
Forgotten changes from 91c88872f8, 6a4c45c0ad and 7b3b4f9b94
Merge pull request #763 from srazi/master

CookieManager::filterString() and some fixes from recent commits.
Revert "[QtWin] using of direct WinAPI call."

It has to be resolved at runtime to provide the same binary
compatibility with Windows versions older than Vista.

This reverts commit 2db89f50bfad33683317128dd8b8eb74c9028ac0.
Fixed hiding navigation container when disable and enabling tabs on top.

Closes #764
Don't use double QUrl::fromUserInput in QupZilla constructor.

Closes #762
Merge remote-tracking branch 'upstream/master' into open-in-new-pb