v2.7.23

• Added data.table to Imports
• Added read_waterdata_stats_por and read_waterdata_stats_daterange to access USGS daily data statistics.
• Updated vignettes, examples, and README to reflect new stats functions.
• Added tests for read_waterdata_stats functions
• Updated next_req_url to allow paging through /statistics API output
• Added deprecation message to readNWISstat function
• Specify "UTC" attribute for returned time
• Added options("dataRetrieval.attach_request" = TRUE) as default to attach the
  request object as an attribute to the returned data frames. Setting
  options("dataRetrieval.attach_request" = FALSE) will return a data frame without
  the request attribute
• Improved time documentation
• Improved error handling in WQP functions
• Added read_waterdata_field_meta, read_waterdata_combine_meta,
  and read_waterdata_channel
• Removed readNWISgwl and readNWISmeas as services have been turned off
• Updated CQL2 templates to allow HUC queries specifically to use a wildcard
  to get multiple inclusive HUCs.
• Add deprecation message to readNGWMN functions. read_ngwmn will be coming soon.