support multi-line image urls

[richardwthompson]

I have been using Gravizo (http://gravizo.com/) in my markdown documents to allow me to incorporate diagrams.

This works great when I use the html / image format ..... but not the markdown format .... I suspect its because pegdown doesn't like multi-line image urls.

Is there any way that pegdown could be updated to support / render multi-line markdown image urls?

E.g. update pegdown to read the following image url such that it calls out to gravizo and displays the image correctly

 ![Alt text](http://g.gravizo.com/g?
  digraph G {
    aize ="4,4";
    main [shape=box];
    main -> parse [weight=8];
    parse -> execute;
    main -> init [style=dotted];
    main -> cleanup;
    execute -> { make_string; printf}
    init -> make_string;
    edge [color=red];
    main -> printf [style=bold,label="100 times"];
    make_string [label="make a string"];
    node [shape=box,style=filled,color=".7 .3 1.0"];
    execute -> compare;
  }
)

![Alt text](http://g.gravizo.com/g? digraph G { aize ="4,4"; main [shape=box]; main -> parse [weight=8]; parse -> execute; main -> init [style=dotted]; main -> cleanup; execute -> { make_string; printf} init -> make_string; edge [color=red]; main -> printf [style=bold,label="100 times"]; make_string [label="make a string"]; node [shape=box,style=filled,color=".7 .3 1.0"]; execute -> compare; })

[vsch]

@richardwthompson, if you need this feature, I have it implemented in a parser I rewrote from commonmark-java to replace pegdown in my Markdown Navigator plugin for IntelliJ IDEs: https://github.com/vsch/idea-multimarkdown. The parser project is https://github.com/vsch/flexmark-java has very detailed source based AST with source offset for every part of the element.

It is CommonMark 0.27 (GitHub Comments) compliant but has parser configuration options to emulate list indentation rules used by: markdown.pl, MultiMarkdown (like pegdown 4 space indents) and kramdown (GitHub Docs). The only extensions that pegdown has that I did not yet implement are: typographic quotes, smarts and definition lists. The rest of the extensions are available, with some extra ones that pegdown does not have.

As an added bonus and what motivated me to switch the parsing is 30-50x faster than pegdown on average documents and several thousand times faster on pegdown's pathological input like [[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[.