Improve the docstring for php-create-regexp-for-method

This patch not only gives the function a more appropriate parameter
name, it also explains the values we expect for that parameter and how
it is acceptable to pass in regular expressions as well.
List all methods via Imenu regardless of their visibility

To find a method using Imenu the programmer must remember its
visibility, e.g. if it was a ‘public’ or ‘private’ method, because we
group methods by their visibility.  If the user does not remember the
visibility then he must look through all of the sub-menus.

This patch adds an ‘All Methods’ entry to the Imenu list that contains
every method in a file, regardless of its visibility.  This makes it
possible for programmers to find methods more easily if they only
remember the name and not the visibility.
Update php-mode-modified for the recent Imenu changes
Merge branch 'imenu-all-methods'

* imenu-all-methods:
  Update php-mode-modified for the recent Imenu changes
  List all methods via Imenu regardless of their visibility
  Improve the docstring for php-create-regexp-for-method