call overloading needs documentation

[mauro3]

Merged PR #8712 came without documentation. Documentation is needed for:

• call itself, probably in the std-lib
• how constructors now work and the relation to convert. In particular constructors for abstract types, new{...},etc

[stevengj]

I added some docs in 11ab1b3 ... does this solve the issue?

[ViralBShah]

The commit above does address the manual part. It would also be nice to have an entry in the stdlib documentation that can be looked up with help.

[stevengj]

Added to stdlib docs by 00bd322.

[mauro3]

Jeff's initial comment on PR #8712 suggests that there is quite a few nifty things which can be done with the new call-feature, for instance his subarray example. Should this not be documented as well?

[mauro3]

Oops, I didn't manage to scroll down. So I'll need to update my comment! Sorry!

OK, so here after properly finishing the read:

The section in doc/manual/types.rst clears up the relation between constructors and conversion. But should it may go into doc/manual/constructors.rst?

The new new{..}(...) syntax in the subarray example still needs explaining though.

[stevengj]

@JeffBezanson moved it to constructors.rst already.

[mauro3]

I think with closing the related #12242, this is also resolved.