Allow app:pref_editLayout

[Mygod]

This allows for implementing an EditTextPreference as in Android 9.0's Wi-Fi AP configuration.

(also I find default value 5 to be nonsensical)

Fixes #181.

[gregkorossy]

Instead of putting those attributes into the XML, they should be contained in the class, like this (maybe at the end of the constructor?):

getEditText().setTypeface(Typeface.MONOSPACE);
getEditText().setImeOptions(EditorInfoCompat.IME_FLAG_FORCE_ASCII);

[Mygod]

I prefer to do it this way so that user can have control over its style.

[Mygod]

@Gericop Please review again. :)

[Mygod]

This PR has been updated according to my idea as per #181.

[gregkorossy]

I'll release 1.0.0 now and add this later because it messes with the AutoSummaryEditTextPreference (it crashes now since getEditText() returns null).