Restructure large nested if statements into more shallow blocks
Factor out contents of if statements to functions for better readability
* viewInfo
* hightlightOrDropArtifact
* split
Before UI always highlighted all slots in both town garrisons even if there no visiting here and you can't actually set army on these slots.
Now garrison slots only highlighted if they're owned by us or our ally. If there no visiting hero in town then only suitable upper garrison slots will be highlighted.
- renamed CAdventureMapButton to more expectable CButton
- merged CButtonBase into CButton
- created more generic class for clickable elements
- created more generic class for selectable elements
- renamed CHighlightableButton to CToggleButton
- renamed CHighlightableButtonsGrous to CToggleGroup
- minimized differences between API of all these classes
- removed all but one contructors in buttons, with same parameters across all classes
