Merge pull request #764 from imincik/slovak

Slovak translation update.
translation update: czech by Jan
translation update: vietnamese
translation update: sv by victor
Also set focus to text box after double clicking lists in vector field dialog
Fix missing alpha picker
Change colour of snap marker to make it easier to see
[QGIS-Server] Add vectorJoins

Vector joins is based on qgsMapLayerRegistry. Vector joins has to be
used for getFeatureInfo and getMap WMS Server Request and for
describeFeatureType and getFeature WFS Server Request.
partly revert 1d5712c4
Slovak translation update.