Time dimensions should be associated with relevant variables in point output files

[kafitzgerald]

Expected Behavior

Variables such as streamflow in for instance CHANOBS and CHRTOUT output files should have proper time and reference_time dimensions.

Current Behavior

Variables such as streamflow do not have proper time and reference_time dimensions. The dimensions are included in the file, but not associated with the necessary variables.

Possible Solution

The time dimension was added by @jmccreight in PR #438.

This will need to be applied for other files / variables and should be part of a broader effort to revisit the output data model.