Envv block

• Erroneous output for [envv.equationalign] has been corrected.
• Output for [envv.equation] and [envv.equationalign] have been added to the latex backend

Example usage for these blocks:

[envv.equation]
....
CONTENT
....

as opposed to

[env.equation]
--
CONTENT
--

The envv option should be used for equation and equationalign to assure accurate rendering of LaTeX.

Better Opal Compatibility

Construct path to the data directory using __FILE__ instead of __dir__ so as to be compatible with Opal. The goal is to have an AsciidoctorJS versoin of Asciidoctor-LaTeX

First beta release

0.1

Update README.adoc