This reverts commit 467fc0dd.

Add schematic decoration force placement flag

Add find_surface_nodes_in_area LUA call which permit to only get the nodes which touch air. This permit to massively improve performance for mods like plantlife

Rebased by Zeno- (conflict in lua_api.txt)

Also add a Lua API and chatcommand for this

Lua-api.txt: Document that paramtype='light' results in light propagation with attenuation and is essential for a light source to spread it's light

Just Markdown, no variant of it. File name intentionally
not changed to “lua_api.md” because of fear to break references
to that file. The file can still be renamed later.

Add minetest.get_mapgen_params()
Deprecate minetest.register_on_mapgen_init()

Also set default height_min/height_max to -31000 and 31000,
respectively, for ore and biomes

Add support for notify-on-decoration
Clean up mapgen constructors
Clean up mapgen.cpp code style somewhat
Remove trailing whitespace from some files

Changes:
  * Add extra documentation for remove_item.

    This isn't as silly as it sounds: iterate a list containing items with
    unique metadata each, and remove_item the first one you find, placing
    into a different - fine, except the remove will invariably remove the
    wrong one, leading to items being duplicated and others destroyed.

    Arguably it's a bug, and Inventory::removeItem should actually remove
    the item you tell it to. (i.e. if the passed ItemStack has metadata,
    match it). But it seems reasonable to just document the behaviour
    more clearly.

 * Improve string_to_pos documentation.
 * Clarify dig_node documentation (return value).
 * Better on_step documentation.
 * get_nodemeta -> get_meta.
 * Other minor fixes.

Signed-off-by: Craig Robbins <kde.psych@gmail.com>

Signed-off-by: Craig Robbins <kde.psych@gmail.com>