Revert of SkRTConf: reduce functionality to what we use, increase simplicity

site/dev/runtime/config.md

+Runtime Configuration Settings
+==============================
+
+Here is a (partial) list of Skia's runtime configuration settings:
+
+## Warning suppression:
+
+* configuration name: images.gif.suppressDecoderWarnings
+  environment variable: skia_images_gif_suppressDecoderWarnings
+  type: boolean
+  description: Suppress GIF warnings and errors when calling image decode
+               functions.  
+  default: true.
+
+* configuration name: images.jpeg.suppressDecoderWarnings
+  environment variable: skia_images_jpeg_suppressDecoderWarnings
+  type: boolean
+  description: Suppress most JPG warnings when calling decode functions.
+  default: false in debug, true otherwise.
+  
+* configuration name: images.jpeg.suppressDecoderErrors
+  environment variable: skia_images_jpeg_suppressDecoderErrors
+  type: boolean
+  description: Suppress most JPG error messages when decode function fails.
+  default: false in debug, true otherwise.
+
+*  configuration name: images.png.suppressDecoderWarnings
+  environment variable: skia_images_png_suppressDecoderWarnings
+  type: boolean
+  description: Suppress most PNG warnings when calling image decode functions.
+  default: false in debug, true otherwise.
+
+## Other:
+
+* configuration name: bitmap.filter
+  environment variable: skia_bitmap_filter
+  type: string
+  description: Which scanline bitmap filter to use \[mitchell, lanczos, hamming,
+               gaussian, triangle, box\] 
+  default: mitchell
+
+* configuration name: mask.filter.analyticNinePatch
+  environment variable: skia_mask_filter_analyticNinePatch
+  type: boolean
+  description: Use the faster analytic blur approach for ninepatch rects
+  default: \?
+
+* configuration name: gpu.deferContext
+  environment variable: skia_gpu_deferContext
+  type: boolean
+  description: Defers rendering in GrContext via GrInOrderDrawBuffer
+  default: true
+
+* configuration name: gpu.dumpFontCache
+  environment variable: skia_gpu_dumpFontCache
+  type: boolean
+  description: Dump the contents of the font cache before every purge
+  default: false
+
+* configuration name: bitmap.filter.highQualitySSE
+  environment variable: skia_bitmap_filter_highQualitySSE
+  type: boolean
+  description: Use SSE optimized version of high quality image filters
+  default: false
+
+## Use:
+
+These configuration values can be changed at runtime by including this in your
+program:
+
+<!--?prettify?-->
+~~~~
+#include "SkRTConf.h"
+/*...*/
+int main() { 
+    SK_CONF_SET( configuration_name, new_value );
+    /*...*/
+~~~~
+
+Or by setting the corresponding environment variable before starting the
+program. For example, in Bourne shell:
+
+<!--?prettify?-->
+~~~~
+#!/bin/sh
+export skia_environment_variable="new_value"
+your_program
+~~~~
+