Silence byte compiler warnings

[sergeyklay]

Hello,

This patch partially solve warnings described in #68.

First, it aims to fix the following warning at byte compiling time:

esup-child.el: Obsolete name arg "esup-result" to constructor esup-result

For more see: https://lists.gnu.org/archive/html/emacs-devel/2018-02/msg00342.html

Also I added missed cl-lib to the Cask file and corrected test/esup-test to require cl if Emacs <= 24.3, otherwise require cl-lib. This fixes the following warning:

Package cl is deprecated

Finally, I fixed the docsstring for esup-child-require-feature-to-filename defun.

/cc @jschaf

[sergeyklay]

Test failed at Travis. This seems is unrelated. For more see #70

[sergeyklay]

Emacs > 25.3 does not work at this time. Build at Travis CI produces the following error:

error while loading shared libraries: libgnutls.so.26:
cannot open shared object file: No such file or directory

Thus, this is disable for now. For more see: https://travis-ci.org/jschaf/esup/jobs/641742587.

Just for reference, there are no errors at GitHub Actions: https://github.com/sergeyklay/bnf-mode/actions/runs/30475202

[jschaf]

Thanks for the PR! I merged it. I think dropping Emacs 25 support is reasonable. Debian stable is on 26.1. I've added you as a collaborator in case you'd like to keep hacking on esup.

[sergeyklay]

Thank you