resolves #89 documented attribute precedence

- added list to quick ref of attribute precedence
- organized attribute subsections in quick ref
- create text substitution section in quick ref
- added attribute precedence section to user manual
- added attribute precedence example to static website section
resolves #123 refactored toc examples

- setup exdir to store example code
- added exdir attribute to header of user manual
- created one file  with example code for each example
- replaced toc example code with appropriate include reference
- updated toc screenshots
- renamed some of the image files
Merge pull request #122 from graphitefriction/attr-precedence

resolves #89 documented attribute precedence
Merge pull request #124 from graphitefriction/toc-example-update

resolves #123 refactored toc examples