Undo whitespace effects when changing coding style

Set `show-trailing-whitespace` to nil & remove
`delete-trailing-whitespace` from `before-save-hook` in all coding styles
except Drupal.

Modify the buffer-local value of `before-save-hook` so it doesn't affect
other buffers.

GitHub-Issue: 53

Signed-off-by: Eric James Michael Ritz <ejmr@plutono.com>
Add unit test for undoing of whitespace effects.

Checks if whitespace effects are undone when changing coding style from
Drupal.

GitHub-Issue: 53

Signed-off-by: Eric James Michael Ritz <ejmr@plutono.com>
Update constant `php-mode-modified`.

Signed-off-by: Eric James Michael Ritz <ejmr@plutono.com>
Merge branch 'github/pr/147'

* github/pr/147:
  Update constant `php-mode-modified`.
  Add unit test for undoing of whitespace effects.
  Undo whitespace effects when changing coding style

GitHub-Issue: Fixes #53
Bump the version number thanks to contributions from Bence Kalmar