Merge branch 'develop' into blockDrag

package.json

src/components/asset-panel/selector.jsx

src/components/gui/gui.jsx

src/components/monitor/monitor.jsx

src/containers/blocks.jsx

src/containers/costume-tab.jsx

src/containers/gui.jsx

src/containers/sound-editor.jsx

src/containers/sound-tab.jsx

src/containers/sprite-selector-item.jsx

src/containers/stage.jsx

src/lib/blocks.js

src/lib/opcode-labels.js

src/reducers/editor-tab.js

src/reducers/gui.js

test/helpers/selenium-helper.js

test/integration/costumes.test.js

test/integration/sounds.test.js

webpack.config.js