agh.sprintf.js: register as an agh module

add test.js

Makefile: generate package directory for "npm publish"

add example.html

add example.js

README: update description of conversions

README: explicitly write agh.sprintf in examples

change code formatting

update README

update README.ja_JP.md

package: publish with npm

README.md: improve English

Update README.md

Update README.ja_JP.md

Update README.md