keepassx2pass: Substitute empty string for None

If keepassx2pass.py is given an xml file containing passwords with an empty
title, like <title></title>, ElementTree.text returns None. This commit
substitutes an empty string; which will produce a password with name '_',
instead of raising AtttributeError, as shown in this exception::

    Traceback (most recent call last):
      File "contrib/importers/keepassx2pass.py", line 80, in <module>
        main(sys.argv[1])
      File "contrib/importers/keepassx2pass.py", line 77, in main
        import_group(group)
      File "contrib/importers/keepassx2pass.py", line 71, in import_group
        import_entry(entry, npath)
      File "contrib/importers/keepassx2pass.py", line 58, in import_entry
        print "Importing " + path_for(element, path)
      File "contrib/importers/keepassx2pass.py", line 37, in path_for
        title = cleanTitle(space_to_camelcase(element.find('title').text))
      File "contrib/importers/keepassx2pass.py", line 16, in space_to_camelcase
        for word in value.split(" "):
    AttributeError: 'NoneType' object has no attribute 'split'
Allow options in EDITOR variable

This is required by most graphical editors, as the shell command they
provide needs to be told to wait until the file has been closed.

This reverts '311c98c9140205f32be2720db9261c67da658c4c'. We thus use
PATH so that the tests still pass in directories with spaces.
darwin: properly ejects ramdisks

In the move away from extensive global variables and improved cleanup
routines, we forgot to fix the darwin platform file, which means
temporary ramdisks never got unmounted. This patch cleans up the general
cleanup trap logic routines.
darwin: fix mktemp argument order
git: do not trap tmpdir removal
edit: Don't go into a crazy loop. Instead prompt.
passmenu: type text with xdotool

Suggested-by: Christoph Egger <christoph@christoph-egger.org>
Use APG instead of pwgen for password generation

APG offers a nice "pronounceable" password generation option, and I'd like to
use it with password-store.
tests: fix t0010 with APG
tests: fix t0500 with APG

APG can't generate passwords longer than 255 characters.