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".

Add engine.gettext() and remove gettext() calls in guiFormspecMenu.cpp

Add old style mod selection in worldconfig dialog

Add missing file headers

Major modmgr overhaul
Add missing formspec checkbox doc

This reverts commit 7dbbbfc6.
(was added twice)

Show server description above connect button instead of in favorites list

Add alphabeticaly sorted worldlists
Select world after creation
Move worldlist handling to separate file
Merge world selection of singleplayer/server tab
Remove some useless code

This reverts commit 39d03148.

Always use address for server
Fix first (empty) element beeing selected after deleting last world

make enter button work in create world dialog