~ecs/hq

sel: enable groups
sel: enable pseudo-elements
Improve multi error handling
Fix send on closed channel
Further deadlock fixes
Send input datum from a separate goroutine

Fixes some deadlocks
Drop unused Expr.String()
s/git.sr.ht/d2evs.net/
Send End datum at the end of the pipeline

Unused by current filters, but will be useful for filters which need to
do something when a channel is closed.
Expr.String: add parentheses for unambiguity
Add multi commands and parentheses

`f1 & f2 > f3` splits the input and passes it to f1 and f2, giving f3
both outputs as input. Parentheses are used to override precedence.
Add . (attribute) filter
Dynamically type filters
Next