Added rake task build:load_order to regenerate .load_order.txt's

* Updated README-DEVELOPERS to describe adding a class to kernel
* Created rake task build:load_order to regenerate the runtime
.load_order.txt files.

README-DEVELOPERS

@@ -16,7 +16,14 @@
   convenience.
 * spec/ and test/ contain tests for verifying that Rubinius implements Ruby.
 
-2. Primitives
+2. Kernel Classes
+
+If you create a new file in one of the kernel subdirectories, it will be necessary
+to regenerate the .load_order.txt file in the equivalent runtime subdirectory in
+order to get your class loaded when Rubinius starts up. Use the rake task
+build:load_order to regenerate the .load_order.txt files.
+
+3. Primitives
 
 To add a primitive:
 
@@ -30,15 +37,15 @@ If your primitive takes variable arguments, you need to provide a wrapper
 method that calls the primitive.  For example Dir::glob calls
 Dir::prim_glob.
 
-3. gdb
+4. gdb
 
 You can run shotgun/rubinius with gdb.
 
 * Run `shotgun/rubinius --gdb`
 * Hit ^C to interrupt
 * Type 'rbt' at the gdb prompt to get a ruby backtrace
 
-4. Specifications
+5. Specifications
 
 RSpec is the machinery behind executing these specs. The intention is to have
 specs for Ruby as a language and set of standard libraries, and to TDD/BDD the

Rakefile

@@ -178,6 +178,9 @@ class CodeGroup
     file @load_order do
       create_load_order(@files, @load_order)
     end
+    task "build:load_order" do
+      create_load_order(@files, @load_order)
+    end
 
     @output << @load_order
   end
@@ -469,6 +472,12 @@ RbConfig = Config
     runtime/stable/platform.rba
   ]
 
+  desc "Rebuild the .load_order.txt files"
+  task "load_order" do
+    # Note: Steps to rebuild load_order were defined above
+    puts "Run rake:build to rebuild .rbc files according to dependency order"
+  end
+
   # OBSOLETE
   task :core => :rbc do
     raise "OBSOLETE. Use 'rake build'"