Merge pull request #2 from takikawa/master

Add dependencies to package metadata
Added root spiral example
Fixed overlap problem
Fixed color-med
Example: rotating triangle with shades from yellow to red
Added first-value
Added Examples section in the docs
Fix bug in pt+
Started reference. Documented points.
Added link to docs
Improved docs
Fixed bug in @
Finished documentation for points and vectors
Moved documentation to github
Added color section to docs
Removed colors.rkt
Added example: Glider - Hacker Emblem
Added color-med*, grid and docs for color operations
Adjust contracts in docs for consistency
Rename duplicated section tag