remove README.tree, the warning is obsolete now

README.tree

@@ -1,49 +0,0 @@
-README file for the "tree" branch of i3
-=======================================
-
-This is a *massive* refactoring of i3. It was driven by thinking about whether
-a different data structure could make things easier (for users and developers).
-The old data structure of a table provided relatively flexible layouts but was
-*very* hard to implement.
-
-The new data structure is a tree. You can have horizontally and vertically split
-containers. Each container can contain either nothing yet (waiting for a window
-or for the user to put more containers in it), one or more containers or exactly
-one window. RandR Outputs and workspaces are not treated specially, but they
-are just containers inside the tree.
-
-This structure allows for easy serialization, meaning multiple things:
-- we can store and reload the layout for inplace restarts (this is already working)
-- we can store parts of the layout and load them at any position in our tree
-  (partly working)
-  - we can load a layout specifying the physical positions of RandR outputs
-    for pathologic screen setups
-  - we can load a default layout for each workspace to specify the position
-    of dock clients
-- we can use test-driven development to a much higher degree because we have
-  access to the whole tree
-
-Ripping out the core data structures of i3 and replacing them of course has
-some side-effects, which I will describe here (the list may not be complete,
-new side-effects may not be known yet):
-- Empty containers are allowed. They can swallow windows based on certain
-  criteria. We can implement session-saving this way.
-- Assignments (put windows on certain workspaces, put workspaces on certain
-  outputs) are just special cases of the point above.
-- Window decorations are now always rendered on the parent window. This means
-  we don’t have to carry around ugly Stack_Windows any more.
-- Operations always (?) operate on containers, so you can make a container
-  (containing multiple windows) fullscreen or floating (for example) and no
-  longer just single windows.
-- All X11 requests are now pushed to X11 in a separate step (rendering is one
-  step, updating X11 another). This makes talking to X11 a lot less error-prone
-  and allows for simpler code.
-
-======================
-SOME WORDS OF WARNING:
-======================
-
-The current state of the branch is not nearly the quality you know of i3. It
-is in flux, changes and crashes are to be expected. Many features do not work
-yet. It is only suitable if you want to help developing or have a look at what
-is coming. Do *NOT* use it for production! You have been warned.