Dimcli

* Improve warning messages for deprecated modules
* Add cumulative warnings to `Dsl.query_iterative`
* Fix for dimcli CLI not showing records previews correctly

* Dimcli module level documentation vastly updated
* See https://digital-science.github.io/dimcli/modules.html
* new `utils` module: misc utilities all grouped under `dimcli.utils`
* `dimcli.shortcuts` is deprecated in favor of `dimcli.utils`
* the pyvis wrapper is now located at `dimcli.utils.networkviz`
* new magic commands:
* `%%dslgsheets`
* `%%dslloopgsheets`
* `%%extract_concepts`
* `%%identify_experts`
* new DSL functions Python wrappers:
* `extract_affiliations`
* `identify_experts`
* `build_reviewers_matrix`
* CLI - command line tool options improved
* options `-w` for webapp search, `-i` for webapp object ID resolver

* Gsheets export shortcuts
* Export DSL results to gsheets: `DslDataset.to_gsheets()`
* CLI command: `.export_as_gsheets`
* `utils.export_as_gsheets` accepts both API JSON and (any) pd.DataFrame
* DSL grammar updated for version 1.28 (2020-09 release)
* Bug fix: json_normalize errors when creating
* Updated DSL grammar for dimcli CLI autocomplete
* fix bug caused by new `_copyright` in JSON response
* `to_json_file` replaces `DslDataset.save_json`

* DSL grammar updated for version 1.27 (2020-08 release)
* Refactoring of grammar objects
* Added methods to save/load JSON data from DslDataset object
* `DslDataset.load_json_file` (class method) and `DslDataset.save_json` (object method)
* `Dsl.query_iterative` takes an extra argument `maxlimit` forcing to stop the iteration when N results have been extracted

* Improve support for iterative queries using DSL `unnest` operator
* Time elapsed info

* DSL grammar updated for version 1.26 (2020-07 release)