Fix up linkcss and copycss semantics

The linkcss attribute copies (and links) the stylesheet, while the copycss attribute embeds the stylesheet. This commit fixes reversed meaning in the documentation.
Merge pull request #121 from shalicke/patch-1

Fix up linkcss and copycss semantics
clarify how to use linkcss and copycss

additionally:
- refactor names of uri attributes
- clarify default behavior
- drop mention of JavaScript