Use getindex for vector creation

[albinahlback]

Now ZZ[1, 2, 3, 4] should create a vector. Still allows for getting generators via S[i]. Will be overloaded with specific methods since this is very generic.

Solves #2052

[thofma]

Isn't R[1] ambiguous? And what about R[:x]?

[albinahlback]

Isn't R[1] ambiguous?

Yes, but it will always default to gens(R, 1).

And what about R[:x]?

It will still work as VarName is stricter than Any.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.36%. Comparing base (2479164) to head (acc4fd3).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2053   +/-   ##
=======================================
  Coverage   88.36%   88.36%           
=======================================
  Files         125      125           
  Lines       31551    31552    +1     
=======================================
+ Hits        27880    27881    +1     
  Misses       3671     3671           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[lgoettgens]

Isn't R[1] ambiguous?

Yes, but it will always default to gens(R, 1).

It is still very unintuitive for users. And as far as I can see, the syntax does not allow to create singleton vectors. (What about empty vectors?)