Add :SyncopateExportToClipboard command

Also, set g:html_use_css to 0, so we get the ugly-but-workable solution
of outputting <font> tags.
Tell the user how many lines were copied
Default mapping now exports directly to clipboard

Users desiring a browser export can define their own mappings.

Fixes #3.
Update README for the new preferred workflow

Closes #11.