Merge pull request #275 from trett/qt4

Qt4
Merge pull request #277 from trett/qt4

[urlpreview] added forgotten header
Merge pull request #279 from trett/qt4

[urlpreview] fix for empty settings
fix cmake errors
[artwork] [vreen] update
Merge pull request #280 from Hamper/qt4

Qt4 backports
fix compile in LTS
Merge pull request #282 from trett/qt4

[urlpreview] fix settings
fix for old cmake
Merge pull request #281 from Hamper/qt4

fix compile in LTS
Merge pull request #290 from trett/qt4

Default value for affiliation and role
Fixed segfault at unit's priority change

Don't overwrite priority's value by unit's one if it's explicitly set by constructor's argument
fix fuckin fix for LTS