Merge LazyJ's changes.
Put all the extra lua files in a src directory.

(This cleans up the folder for users, who don't want to see all those
strange files)
Add snow.place back. Use place_node for creating new nodes.
Consolidate readme's.

Put LazyJ's Readme in a seperate changelog.
Workaround for plantlife bug.
Fix up snow a bit, allow placing/digging multiple levels.
Make snow drop moss again.
Make ice freezeover water when placed. Also make water pointable with ice.
Keep dirt_with_snow blocks after snow destruct.
Bump to version 3.0 for the next release.