Support positive count in Readdir() (rakyll#61)

Follow on rakyll#60.

The Readdir() should support positive count in order to return the specified counts of files.

For it, I defined statikFS.dirs and httpFile.dirIdx for managing the internal state and use it inside Readdir().

Add support for package comment (rakyll#51) (rakyll#52)

Several linting tool warn about missing package level comments so
write one by default.

Add directory support (rakyll#46)

Use latest patch releases (rakyll#28)

Allow changing package name (rakyll#45)

Allows changing the name of the generated package.