changed Greek names of headings and lists to three letters
fixed subheading Object
fixed subheadings in HTML documents

closes #28
Merge branch 'fix#28-headings' into develop

Conflicts:
	blog/classical-music.html
	blog/dog-training.html
	blog/headings.html
	blog/math-changing-world.html
	blog/semantic-punctuation.html
	core/doc/typo.html