* pcomplete-extension.el: New approach by Redefining shell-command-completion-function.
(shell-command-completion-function): redefine.
(pcomplete-command-name): return the last exec found on command line.
* pcomplete-extension.el (pcomplete-command-name): Fix, take care of embeded command that maybe itself executables.
e.g apt-get install.
* pcomplete-extension.el (pcomplete/sudo): Check if we complete command using pcomplete-command-name.
(pcomplete-command-name): Handle `cd', `pushd' and `popd' which are not available in executable-find nor which.