Feature/ncextract enhancement

[casadoj]

I have done some changes in the ncextract tool:

1. Now it produces one file (NetCDF or CSV) for each point of interest. Before, it used to produce one single file with all the points of interest together, which prevented following the development of the process, and caused loss of computing time when the tool stopped before finishing, so there was no output at all.
2. I've added a filter based on the start and end of the study period. This solves partially issue Add filter by time in ncextract and catchstats #71
3. I've added a flag (-i or --inflow) to be able to extract the inflow to reservoirs and lakes. When flagged, the tool extracts and adds the time series at all the pixels directly upstream of the provided coordinates. Otherwise, the tool extracts the outflow of the reservoir or lake.

I have updated the test and the documentation in the Wiki.

[doc78]

@casadoj Can you please change the base of the pull request to "development"?

[casadoj]

@doc78 changed to development. I hope it's fine now.