Add Tramp test

Add Tramp test

* doc/misc/tramp.texi (Remote processes): Fix typo.

* lisp/shell.el (shell): Fix typo.

* lisp/net/tramp.el (tramp-set-connection-local-variables): Simplify.

* test/lisp/net/tramp-tests.el (tramp-test30-explicit-shell-file-name):
New test.
(tramp--test-special-characters, tramp--test-utf8): Adapt docstring.
(tramp-test31-vc-registered)
(tramp-test32-make-auto-save-file-name)
(tramp-test33-make-nearby-temp-file)
(tramp-test34-special-characters)
(tramp-test34-special-characters-with-stat)
(tramp-test34-special-characters-with-perl)
(tramp-test34-special-characters-with-ls, tramp-test35-utf8)
(tramp-test35-utf8-with-stat, tramp-test35-utf8-with-perl)
(tramp-test35-utf8-with-ls)
(tramp-test36-asynchronous-requests)
(tramp-test37-recursive-load, tramp-test38-unload): Rename.