Some functions and changes

[vincenzocoia]

This pull request comes with three changes:

1. A modified version of ch_regime_plot() (ch_regime_plot2()) so as not to depend on a specific data frame format as an input.
   • For example, can't easily use the original function if data are retrieved from tidyhydat.
2. A function I like using called ch_ams_timeseries() to visualize a time series of annual maxima. Especially useful for making implicit NA's explicit, so that the line plot breaks when data for a year is missing.
3. A scale_*_gumbel*() family of functions meant to be added to a ggplot object to put return period or AEP on reduced Gumbel variate spacing.

Regarding the regime plot, this is meant to generate a discussion regarding what to do about this new way of engaging with the function, especially since other plotting functions have the same problem.

[KevinShook]

Hi Vincenzo
Sorry that it's taken me so long to look at your pull request.
A few comments:

• the conflicts noted above
• errors in the check() log file
• is it necessary to have the function ch_regime_plot2(), when we have the function ch_tidyhydate_ECDE?
• it would be nice to have the function ch_ams_timeseries have a slightly more meaningful name indicating that it is a plotting function, and to have the example use an actual time series

[KevinShook]

00check.log
Here's the check() log. Do you have an older version of ch_catchment_hyps?