Introduced Code Snippet and Code Snippet GeSHi guides.
Fixed some typos.
Code snippet guides added to guides.json.
Improvements for code snippets guides.
Added missing image.
Minor text changes / section link corrected.
Fixed typo.
Changed codestyle of PHP sample.
Code Snippet guide revised.
Code Snippet GeSHi documentation revised.
Changed headline explaining how to apply highlighting at output page.
Minor change in dependencies for Code Snippet GeSHi guide.
Reverted change of the headline for output page highlighting.
Merge branch 't/11480'