Update 0.38 — Arcane Worlds Steam update #618302

This update brings some optimizations and a new world type (mountains). The game now uses vertex shader textures, so I had to drop support for some old Radeon cards that don't support this feature. Change log: New world type: mountains. Using vertex shader textures for height map and water foam flow (moving some calculations to GPU). Smoother nearby land (clamped bicubic interpolation). Culling out-of-view land, water and lava. Fixed guard tower shooting at mana gatherers. Various minor improvements.