create_feature: create_feature
In analysr/analysr: Analysr

This function create a new coll named with the description tag in the stat_units table. The function will extract feature form the measure table. You need to specify which tag you want, in which period you want to execute the aggregation method and which col name you want in the stat_units table.

create_feature(
  model,
  tag_to_create,
  wanted_tag,
  start,
  end,
  aggregation_method = mean_aggregate
)

`model`	An AnalysR model
`tag_to_create`	Label to write in the stat unit table
`wanted_tag`	The name of the measures we want to work on
`start`	A date marking the beginning of the studied time period.
`end`	A date marking the end of the studied time period.
`aggregation_method`	A function to aggregate data. Default: mean_aggregate