Update plantuml to version 8002
Ignore testing directory
Add support for Block/Act/Seq/Nwdiag
Deduplicate extension code
Add support for SVG viewbox based width/height extraction
Fix #38 Invoke graphviz directly rather than through plantuml.
Merge pull request #40 from pepijnve/master

Misc fixes
Add changelog note for graphviz bugfix
Merge branch 'master' into asciidoctor-1.5
Change version number to 1.2.0
Change asciidoctor dependency to 1.5.0 final
diagram.rb cleanup