Rename "normal" theme to "islands"

closes #1038
README: BH link fixed
Merge pull request #1041 from bem/issues/1038@v2

Rename "normal" theme to "islands"
popup: increase negative margin which prevents scrolling when big popup hidden
Merge pull request #1036 from bem/incerase-popup-margin

popup: increase negative margin which prevents scrolling when big popup is hidden
Updated `enb-bem-docs` to `0.5.4`
button: Fix jsDoc for button_type_link
Merge pull request #1051 from bem/issues/1050@v2

button: Fix jsDoc for button_type_link
Merge pull request #1049 from bem/issues/1048@v2

Updated `enb-bem-docs` to `0.5.4`
Upgrade Gemini to 0.8.2
Updated gemini screens