rm tabindex

We use `tabindex` in many places. Unfortunately this does not improve the situation. `tabindex` should only be used if tab order must for some reason be different from order of html elements.

So this removes `tabindex` completely and uses `autofocus` instead where appropriate. In a simple formular:

```
s/tabindex="1"/autofocus="autofocus"/
s/ tabindex="[^"]*"//
```