fix error output, when execution err is nil

update tests, fix error print bug

Merge branch 'master' of https://github.com/gopherds/gophernotes

errors from out of order var declarations

Merge branch 'master' of https://github.com/gopherds/gophernotes

Merge pull request gopherdata#41 from gopherds/refactor

block importing

Merge pull request gopherdata#36 from gopherds/refactor

import improvements, linting

Update README.md