Manage exported functions
Currently, all the functions are exported to facilitate development. Thus, they are listed in the manual.
However, it is not relevant to do so, especially for the `plot*()` functions.
In addition, I am not sure that it is relevant to create `plot` S3 methods for `HN`, `RR` and `TA` objects just to manage the type of plot.
Maybe it could be managed inside the `plot.ts_meteo()` function. It could simplify the readability of the index of the package functions for the user. Especially since the user never consciously manipulates these objects.
Maybe it is enough to keep only `plot.ts_hydro()` and `plot.ts_meteo()`.
Maybe it could be the same for the `regime` S3 methods.
I don't know if we should split the 'hydro' and 'meteo' functions.
I think that it more readable and easier to manage, but the code and documentation are sometimes a bit redundant.
The 'meta()` function is not currently splited `metats_hydro()` and `meta.ts_meteo()`.
By the way, it would be possible to detect automatically if it is a hydrological or meteorological feature by checking the feature code:
```r
# hydro
grepl("^\\d", "Y1234567")
[1] FALSE
# meteo
grepl("^\\d", "12345678")
[1] TRUE
```
issue