v0.2.4

Changelog

87b18ee Add _ Jsonnet var extending std with usefull functions
e368ecf Add debug stream task
645e51f Add env var override for default output/input format
0747732 Add support for Jsonnet file arguments to eval scripts.
d4f3ad9 Ensure null values are propagated
eda576e Fix deadlock issues on task errors
a312a19 Fix reading from stdin without requiring -
5948385 Use RawValue.MarshalJSONString() for eval