feature: html + css - sub-menu added in user panel + styles

src/header.pug

src/index.pug

src/interactions.html

src/styles/hubl-app/_index.scss

src/styles/hubl-app/content/_index.scss

src/styles/hubl-app/header/_index.scss

src/styles/hubl-app/left-nav/_index.scss

src/styles/hubl-framework/commons/_index.scss

src/styles/hubl-framework/commons/borders.scss

src/styles/hubl-framework/commons/lists.scss

src/styles/hubl-framework/commons/user-thumb.scss

src/styles/hubl-framework/forms/inputs.scss

src/styles/hubl-framework/icons/_index.scss

src/styles/hubl-framework/icons/custom-icons.scss

src/styles/hubl-framework/icons/material-design-icons.scss

src/styles/hubl-framework/icons/positions.scss

src/styles/hubl-framework/icons/simple-line-icons.scss

src/styles/hubl-framework/links/_index.scss

src/styles/hubl-framework/segments/sizes.scss

src/styles/index.scss