Terraforming update (4)

Add 3d caves using 3d perlin noise
Only 2 old cave systems
Auto-select player spawn position

Seaweed and always-forget DEBUG variable

Add an ABM for growing of seaweed
Fix default of DEBUG variable

Decoration update

Add seaweed
New bedrock texture
Add "... Wood" on every built-in tree
Fix global variable leak
A little bit tune to few biome
Remove "NIL (Biome?)" biome
Better statistic on start
Tidy up!

Bug in README

Fix:
- biome count
- `bakedclay` mod support

Terraforming update (3)

Biome temperature and humidity update.
Terraforming update: simplified height calculations, remove fissure, add plateau.
Less noise.
Leafdecay bugfix.
Better ore generation.
Update README.

Update README

Delete jpg.jpg

Don't know why this file get uploaded.

Terraforming update (2)

Add some space near river that cut through terrain. Applying Krock's suggestion (See https://forum.minetest.net/viewtopic.php?p=153371#p153371).

PS: still takes long time to generate

Ore placing bugfix. Changed HMIN, HMAX, BEDROCK, BEDROCK2 default par…

…ameter. HUD bugfix. Fix README