CMFM: Fix change to root when initial directory not exists

Fix also R.string.msgs_settings_invalid_initial_directory string for default string.xml file

Change-Id: I35ddf7f1ca2b250638ea96bfee894de9f07ed5b9
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
CMFM: Wait indefinitely on privileged console allocation

Wait indefinitely if a privileged console is being allocated. Wait for
the user response to SuperUser or SuperSu prompt (or whatever it is).

Change ShellConsole.this access to a private variable in methods of ShellConsole

Change-Id: I6752fe8bcd0de3aa6478ad97fb84c9ac8697a970
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
CMFM: Support for Intent.ACTION_SEND_MULTIPLE

This changes allows to send multiple files through selecting
multiple files. Add new "Send selection" global menu, that is shown
when user has some selected files, and all of them are files (send multiple
is not allowed for folders)

Change-Id: I1a889c1188803a6639433d4613fec2246d90fc9b
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
Don't prompt for superuser access when picking a file.

The file picker is chrooted anyway, so it's confusing to the user to see
a superuser prompt in that case.

Change-Id: Ied492fc2270a343e17057efd252606f230d02180
Allow picking of directories.

This is used e.g. by k-9 to select an attachment storage path.

There are a number of intent filter conventions for picking directories.
In k-9's code I found the following:

- action org.openintents.action.PICK_DIRECTORY, scheme file
- action com.estrongs.action.PICK_DIRECTORY, scheme file
- action Intent.ACTION_PICK, scheme folder
- action com.androidworkz.action.PICK_DIRECTORY, scheme file

Implemented is the third variant, as it's the most generic way to
describe the intention.