Better YAML support

- Parse any yaml with PyYAML
- Add builtin yaml keyword references for specifying references
- Add builtin yaml keyword basepath for specifying base path for image
sources and such
- yaml title keyword changes html title
- All other keywords are put into a meta object to create meta html tags
- Actually retrieve meta variables from Python Markdown “meta”
extension and merge with yaml meta (yaml meta overrides “meta” extension
- Fix for ST2 super reload problem
- Fix for ST2 choking on using pkutil on “yaml.lib3”
- Add test markdown for testing features
Typo fix
Test web and local images
Add 'destination` save path in yaml frontmatter
Add attribute list visual test
Simplify CSS rules

- Remove unnecessary specifiers
- Reduce combine rules to reduce redundancy
Remove unneeded backtick rule
Pre and Table horizontal scroll

- Pre tags are now scrollable when overflowing
- Tables are scrollable when overflowing
ignore html files in tests folder
Update test file settings and comments
Handle super the same for ST2 and ST3
Document YAML feature
Fix: embedded font broken on latest chrome
Merge pull request #226 from facelessuser/master

Better Yaml support and other enhancements