Update SkFlattenable buffers to be more modular.

This CL is an effort to stage the conversion to named
parameters for all SkFlattenable commands. This particular
stage only does the following two things...

1. Move flattenable buffers from SkFlattenable.h into
   their own header.
2. Update and Add new read write methods for better clarity
   and convenience.

BUG=

Review URL: https://codereview.appspot.com/6448095

git-svn-id: http://skia.googlecode.com/svn/trunk@4980 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/ClockFaceView.cpp b/samplecode/ClockFaceView.cpp
index 7d4da10..a719608 100644
--- a/samplecode/ClockFaceView.cpp
+++ b/samplecode/ClockFaceView.cpp
@@ -8,6 +8,7 @@
 #include "SampleCode.h"
 #include "SkView.h"
 #include "SkCanvas.h"
+#include "SkFlattenableBuffers.h"
 #include "SkGradientShader.h"
 #include "SkPath.h"
 #include "SkRegion.h"
diff --git a/samplecode/SampleAll.cpp b/samplecode/SampleAll.cpp
index 303059b..9644e79 100644
--- a/samplecode/SampleAll.cpp
+++ b/samplecode/SampleAll.cpp
@@ -18,6 +18,7 @@
 #include "SkDashPathEffect.h"
 #include "SkDiscretePathEffect.h"
 #include "SkEmbossMaskFilter.h"
+#include "SkFlattenableBuffers.h"
 #include "SkGradientShader.h"
 #include "SkImageDecoder.h"
 #include "SkLayerRasterizer.h"
diff --git a/samplecode/SampleSlides.cpp b/samplecode/SampleSlides.cpp
index 1154c76..54a9cf9 100644
--- a/samplecode/SampleSlides.cpp
+++ b/samplecode/SampleSlides.cpp
@@ -9,6 +9,7 @@
 #include "SkView.h"
 #include "SkCanvas.h"
 #include "SkDevice.h"
+#include "SkFlattenableBuffers.h"
 #include "SkPaint.h"
 
 #define BG_COLOR    0xFFDDDDDD
diff --git a/samplecode/SampleText.cpp b/samplecode/SampleText.cpp
index db4dbea..7d192f4 100644
--- a/samplecode/SampleText.cpp
+++ b/samplecode/SampleText.cpp
@@ -9,6 +9,7 @@
 #include "SkView.h"
 #include "SkCanvas.h"
 #include "Sk64.h"
+#include "SkFlattenableBuffers.h"
 #include "SkGradientShader.h"
 #include "SkGraphics.h"
 #include "SkImageDecoder.h"
@@ -134,11 +135,11 @@
     void init(SkScalar exponent);
     SkPowerMode(SkFlattenableReadBuffer& b) : INHERITED(b) {
         // read the exponent
-        this->init(SkFixedToScalar(b.readS32()));
+        this->init(SkFixedToScalar(b.readFixed()));
     }
     virtual void flatten(SkFlattenableWriteBuffer& b) const SK_OVERRIDE {
         this->INHERITED::flatten(b);
-        b.write32(SkScalarToFixed(fExp));
+        b.writeFixed(SkScalarToFixed(fExp));
     }
 
     typedef SkXfermode INHERITED;
diff --git a/samplecode/SampleTextEffects.cpp b/samplecode/SampleTextEffects.cpp
index 2151548..b2feae7 100644
--- a/samplecode/SampleTextEffects.cpp
+++ b/samplecode/SampleTextEffects.cpp
@@ -8,6 +8,7 @@
 #include "SampleCode.h"
 #include "SkView.h"
 #include "SkCanvas.h"
+#include "SkFlattenableBuffers.h"
 #include "SkGradientShader.h"
 #include "SkPath.h"
 #include "SkRegion.h"