Merge pull request UB-Mannheim#69 from UB-Mannheim/eslint

Use eslint for js code style

Increase PKG_VERSION to 0.2.1, created release files

The release files (tar.gz+zip) are created with `make release`
and uploaded to the new release in github:

https://github.com/UB-Mannheim/ocr-fileformat/releases/tag/v0.2.1

Merge pull request UB-Mannheim#31 from UB-Mannheim/before-release

Prepare new release

Signed-off-by: Stefan Weil <sw@weilnetz.de>

alto2 -> alto3

Symlink hOCR-to-ALTO