Link Text Renderer

A tiddlyweb renderer that turns plain text into more plain text,
but with WikiLinks, FreeLinks and URLs turned into HTML links.

The goals is to write with the veracity and cogency that plain
text provides, but still get the benefits of links

See http://cdent.tiddlyspace.com/PlainTextWiki for the original
record of this version of idea.

To use add to wikitext.type_render_map in tiddlywebconfig.py:

    'wikitext.type_render_map': {
        'text/x-linkedtext': 'tiddlywebpugins.ltr',
    },

Note that the type is a stub. That might not be the right type.

Or use the plugin as a system_plugin:

    'system_plugins': ['tiddlywebplugins.ltr']