Res2df

* Compatibility with OPM 2021.04
* When parsing WELOPEN with lumped connections, `ecl2df.compdat` will fail hard instead of returning erroneous data.

* Refactor zonemap parsing for use in other projects
* Use NaN in dataframes where libecl grid output otherwise gives 1e-20.

Bugfix for ERT integration of csv2ecl summary.

The command line API for csv2ecl summary was not compatible with the ERT integration and has been changed. The ECLBASE argument is now supplied as --output, similar to the other csv2ecl subcommands.

Also add possibility for csv2ecl to write to subdirectories.

Fixes:
* Bugfix for gruptree module, solving issues with multiples trees. Refactored, and incurs deprecation of one function.
* Revert deprecation for non-datetime indices in summary module introduced in last version. Added workarounds for supporting Eclipse summary files going beyond year 2262, which is tricky in Pandas.

Breaking changes:
* In fipreports, the column "WATER_TOTAL" has been renamed to "WIIP_TOTAL".

New features:
* ECL2CSV forward model now supports options supplied from ERT config file.
* Dataframe objects returned from summary.df() have metadata for each column vector attached in a dict in df.attrs["meta"].
* All command line tools can output to stdout by providing the magic filename "-".
* WSEGVALV keyword is supported in the compdat module.
* summary.df will give warning if datetime=True is not supplied. In the future, the returned dataframe will always have a datetime index. This does not affect CSV export.

Bugfixes:
* Fix PVTG include file export

Bugfix release: Avoid crash with WSEGSICD support from v0.8.3