Use batch updates for HGrid#addData.

Lazy-loading lots of data is potentially very slow, since the DataView
updates after each addition. Use DataView#beginUpdate and
DataView#endUpdate for faster lazy-loading.
DRY up changes; h/t sloria.
Merge branch 'hotfix/batch-update'
Merge branch 'hotfix/batch-update' into dev
Bump version
Merge branch 'master' into dev