py3: fix DeprecationWarning of imp in sage.misc.inline_fortran

[embray]

This adds a new _import_module_from_path that encapsulates the existing code from this module for searching a directory for a module and importing it, but implements in both Python 2 and Python 3(.4+) compatible ways.

I think in theory this utility could be made public, and moved to a more general module, but I couldn't decide where so I just left it here for now. Maybe if another use case is found for it...

Component: python3

Author: Erik Bray

Branch/Commit: 8261915

Reviewer: Frédéric Chapoton

Issue created by migration from https://trac.sagemath.org/ticket/25703

[embray]

Commit: 8261915

[embray]

New commits:

8261915

py3: adds a _import_module_from_path helper function

[embray]

Changed branch from u/embray/python3/sage-misc-inline_fortran/module-importSwitched to u/embray/python3/sage-misc-inline_fortran/module-import

[fchapoton]

comment:3

is this a (better) duplicate of #25599 ?

[fchapoton]

comment:4

ok

[fchapoton]

Reviewer: Frédéric Chapoton

[embray]

comment:5

I believe this issue can reasonably be addressed for Sage 8.4.

[vbraun]

Changed branch from u/embray/python3/sage-misc-inline_fortran/module-import to 8261915