remove left-over references to PNG generation

Author: pkra

.gitignore

@@ -1,6 +1,4 @@
 .DS_Store
 node_modules
-batik/*
-!batik/README.md
 mathjax/*
 !mathjax/README.md

README.md

@@ -1,15 +1,15 @@
 # mathjax-node [![Build Status](https://travis-ci.org/mathjax/MathJax-node.svg?branch=develop)](https://travis-ci.org/mathjax/MathJax-node)
 
-This repository contains files that provide APIs to call [MathJax](https://github.com/mathjax/mathjax) from 
-node.js programs.  There is an API for converting individual math 
-expressions (in any of MathJax's input formats) into SVG images or MathML 
-code, and there is an API for converting HTML snippets containing any of 
+This repository contains files that provide APIs to call [MathJax](https://github.com/mathjax/mathjax) from
+node.js programs.  There is an API for converting individual math
+expressions (in any of MathJax's input formats) into SVG images or MathML
+code, and there is an API for converting HTML snippets containing any of
 MathJax input formats into HTML snippets containing SVG or MathML.
 
 See the comments in the individual files for more details.
 
-The `bin` directory contains a collection of command-line programs for 
-converting among MathJax's various formats.  These can be used as examples 
+The `bin` directory contains a collection of command-line programs for
+converting among MathJax's various formats.  These can be used as examples
 of calling the MathJax API.
 
 Use
@@ -18,10 +18,7 @@ Use
 
 to install mathjax-node and its dependencies.
 
-These API's can produce PNG images, but that requires the
-[Batik](http://xmlgraphics.apache.org/batik/download.html) library.  It 
-should be installed in the `batik` directory.  See the README file in that 
-directory for more details.
+These API's no longer produce PNG images but can easily be integrated into workflows using svg-to-png converters (e.g., png2svg, librsvg, batik).
 
 # Getting started
 
@@ -52,7 +49,7 @@ mjAPI.typeset({
 ```
 
 
-* `./lib/mj-page.js` is optimized for handling full HTML pages. 
+* `./lib/mj-page.js` is optimized for handling full HTML pages.
 
 
 ```javascript