Extend function domain with some symbolic function calls

[rwst]

The ticket implements an idea from #24428 to allow symbolic functions to always extend their domain when necessary, in order to return the most information from the call.

Practically if the extend_for() attribute of the Function exists it is called with the function arguments. If returned True then, instead of trying x.func() we try parent.complex_field(x).func().

Component: symbolics

Author: Ralf Stephan

Branch/Commit: u/rws/extend_function_domain_with_some_symbolic_function_calls @ 3bfcc88

Issue created by migration from https://trac.sagemath.org/ticket/24832

[rwst]

Branch: u/rws/extend_function_domain_with_some_symbolic_function_calls

[sagetrac-git]

Commit: 3bfcc88

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

3bfcc88

24832: add doctest

[rwst]

Author: Ralf Stephan

[mkoeppe]

Branch has merge conflicts