Texture names must now be escaped in formspec elements image[],
background[], image_button[], image_button_exit[].

Instead of special-case handling of texture loading (and unloading
which was missing) in guiFormSpecMenu.cpp, use the newly created
ISimpleTextureSource interface which is a minimal subset of
ITextureSource. There is an implementation of this interface
used by GUIEngine (MenuTextureSource).

Fix an off-by-one bug in unescape_string; it caused requests for a
texture called "\0".

On the lua side, notably minetest.env:<function>(<args>) should now
be replaced by minetest.<function>(<args>).
The old way is and will stay supported for a long time.

Also:
Update and clean up lua_api.txt (by celeron55)
Move EnvRef to lua and remove add_rat and add_firefly (by kahrl)
Add separate src/util/CMakeLists.txt, other minor fixes (by kahrl)

Framework for the attachment system, new object property which allows changing the color and alpha of mesh materials

New object property which allows changing the color and alpha of mesh materials. Due to the current lighting systems it doesn't work yet, but the full implementation is there

Framework for the attachment system, with no actual functionality yet

Send bone and player object to the setAttachment function in content_sao.cpp, but we need a way to translate it there and send it to the client

I will also want position and rotation offsets to be possible to apply to attachments

Network object ID from server to client. This will be used to identify the parent client-side and know what to attach to

Blacklisted characters are: / \