Redo the _whooollleee_ build system

Following the tutorials on http://www.ostricher.com/tag/scons/, I rebuilt the
build system so that SConscript files are *much* easier to write.

site_scons/site_tools/test.py

@@ -0,0 +1,51 @@
+# test.py
+# Eryn Wells <eryn@erynwells.me>
+
+'''
+Test builder for SCons. Test files are compiled to objects and stored in the 
+environment.
+'''
+
+def _process_test_dir(env, dir, program=None):
+    # TODO: Builder for test directories?
+    pass
+
+
+def _build_test_object(env, source, program=None):
+    obj = env.Object(source)
+    if not program:
+        program = 'test'
+    try:
+        env.test_objects(program).extend(obj)
+    except TypeError:
+        env.test_objects(program).append(obj)
+    return obj
+
+
+def _build_test_program(env, name=None):
+    if not name:
+        name = 'test'
+    prog = env.Program(name, env.test_objects(name), LIBS=[env.lib('gtest')])
+    env.register_test_program(name, prog)
+    return 
+
+
+def _run_tests(env, name=None):
+    if not name:
+        name = 'test'
+    cmd = env.Command(env.test_program(name), None, '$SOURCE --gtest_color=yes')
+    env.AlwaysBuild(cmd)
+    return cmd
+
+#
+# SCons tool interface
+#
+
+def generate(env):
+    env.SetDefault(TESTS={})
+    env.AddMethod(_build_test_object, 'Test')
+    env.AddMethod(_build_test_program, 'TestProgram')
+    env.AddMethod(_run_tests, 'TestRun')
+
+def exists(env):
+    return 'Object' in env