[select]: added passing tabindex to button block

Fixes #1174
[select]: specs for tabindex
README: CleanCSS
README: dev server
README: coding style
Merge pull request #1175 from zxqfox/feature/select-tabindex

added passing tabindex to button block
[image] div => span in tmpl-specs

Fixes #1192
[select] fixup tabindex tests according to button aria-hidden
Merge pull request #1193 from zxqfox/hotfix/image-tests

Hotfix/image tests
[link] add sizes for islands theme

Fixes #1182
add link to islands page with all 4 sizes
change link size in showcase to large
[link] add _size to docs
Merge pull request #1195 from zxqfox/feature/link-size-modifier

link: add sizes for islands theme
new block: progressbar