crashday 3d editor

New Features:

• new manual forming tool: areal forming
• new forming mode: Profiles
• new copying system
• setting height of copied vertices
• selecting one point at the time in profile mode

Fixes:

• handling non-squared markings
• mistakenly marked vertex points (e.g through mountains)
• wrongly applied restrictions to certain tiles (thanks Dawid)
• mirrored tiles having mirrored restrictions (thanks Dawid)
• other shenanigans
• Left ctrl picks up tile under cursor even if current element is null
• neighbour != null save error
• form modes not working after reload
• inefficient track loading