Add placeholder StringProperty to TextInput widget.
Merge branch 'master' into placeholder
Add basic placeholder functionality.
Add placeholder_color ListProperty.
Refresh placeholder text on widget size change.
Edit TextInput style to respect placeholder_color.

Use a lighter grey for default placeholder_color.
Make placeholder text respect font_name and font_size.
Rename 'placeholder' -> 'hint_text'.
Show hint_text when password=True.
Add hint check to codeinput's _create_line_label.
Add version added to hint_text and hint_text_color properties.
Correct versionchanged to versionadded.
Replace resource intensive check for empty text property.
Merge pull request #966 from Ian-Foote/placeholder

Placeholder