Add container element to create three-column layout
Construct three column layout without calc - directive
Use constant to define feature attribute panel width
Name constant semantically
Remove redundant constant
Define common styles in shared class definition
Reuse common definition in panel style
Move feature attributes panel definition to less in order to use less constants
Remove redundant pixel definitions when measure is zero
Merge branch 'master' of https://github.com/finnishtransportagency/digiroad2 into improve_asset_creation