markdeep suggestions

gistfile1.txt

By adding the following small snippet at the top of markdeepToHTML markdeep can sortof support local file insertion when being run in node.js.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
function markdeepToHTML(str, elementMode, local_file_handler = undefined) {
    // If a local file handler is specified, resolve '(insert src here)' directly when possible'
    // Only expected to be used when run as script via node.js
    if (local_file_handler !== undefined) {
        str = str.rp(/(?:^|\s)\(insert[ \t]+(\S+\.\S*)[ \t]+here\)\s/g, function(match, filename) {
          var content = local_file_handler(filename);
          if (content === undefined) {
            // Leave unchanged!
            return match;
          } else {
            return content;
          }
        });
    }
  ...
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Using it looks like this:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs = require('fs'); // file system

function local_file_handler(filename) {
	var fn = 'docs/' + filename;
	try {
		var content = fs.readFileSync('docs/' + filename, 'utf8');
		console.log('  Successfully inserted ' + fn);
		return content;
	} catch (err) {
		console.log('  Failed to insert ' + fn + ', error ' + err);
		return undefined;
	}
}

content = window.markdeep.format(data, false, local_file_handler);
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Caveat 1 - Assumes utf8 source documents
----------------------------------------
I'm not sure how to detect encoding of source document in node.js and it is not specified in the insert statement.
I should probably open it in ascii and see if there is a meta-tag first.

Caveat 2 - Assumption no markdeep script tag
--------------------------------------------
Currently assumes that there is no markdeep-loading script in the file being inserted.
That is no markdeep-script-tag.
I think it would be nice to solve that here but not sure how to exactly.

If the use case is to support server-side execution from node.js then maybe it is ok to not have it in the source files.

I already assume 2 in the main document for the [offline processor](https://github.com/breakin/markdeep-offline) but I think it would be nice to lift it here.

Caveat 3 - Security etc
-----------------------
The link is not verified so this should only be run on on documents you trust or in a sand-box.
I would probably move the validation to the local_file_handler-function so markdeep itself doesn't have to grow.

Note that encoding of source document could also fall to the local_file_handler-function. I think the important thing is that it must be well-specified in what encoding the local_file_handler is supposed to return the content in.

Here is a commit to markdeep-offline breakin/markdeep-offline@5012aeb
It also "fixes" (in a very naive way) caveat 2 by removing any line starting with .