Update the Layoutlib API to contain part of the current config.

Right now only the screen size is needed. We can add more to Params
as needed.

Since we should use the existing enum classes for this, I moved
all the current enum from sdklib into a new jar file called
resources.jar.

ADT, sdklib, layoutlib_api all depend on it.

Changes to resources should always be API compatible and the result
should be copied into the in-dev platform branch in prebuilt, similar
to layoutlib_api. See the README.txt files in layoutlib_api/ and
resources/

Change-Id: I877ba3cad555ec497954bb0866639e51e7751020
diff --git a/layoutlib_api/README.txt b/layoutlib_api/README.txt
new file mode 100644
index 0000000..487a1a2
--- /dev/null
+++ b/layoutlib_api/README.txt
@@ -0,0 +1,16 @@
+LayoutLib API is a jar describing the API used to load and interact with layoutlib.jar
+It is to be packaged with clients accessing layoutlib.jar
+
+Layoutlib.jar is built from frameworks/base.git and therefore is versioned with the platform.
+
+IMPORTANT NOTE REGARDING CHANGES IN LAYOUTLIB_API:
+
+- The API must stay compatible. This is because while layoutlib.jar compiles against it,
+  the client provides the implementation and must be able to load earlier versions of layoutlib.jar.
+  This is true for all the classes under com.android.ide.common.rendering.api and
+  com.android.layoutlib.api although the latter is obsolete and should not be changed at all.
+
+- Updated version of layoutlib_api should be copied to the current in-dev branch of
+  prebuilt/common/layoutlib_api/layoutlib_api-prebuilt.jar
+  The PREBUILT file in the same folder must be updated as well to reflect how to rebuild this
+  prebuilt jar file.
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