In later versions of Xcode changing the NSTextFieldCell to an NSSecureTextFieldCell generates an error (no longer secure).
Rather than maintain two almost identical field types, GYB is being used to templatize the primary source file 'DSFFloatLabelledTextField.swift.gyb' into two different classes.
As a result, changes _must_ be made to the template file rather than the sources.
1. Some tweaks to improve RTL handling
2. Added ability to add additonal spacing between placeholder and text (placeholderSpacing)
3. Fixed issue where dynamically-created fields weren't being created correctly.
4. Fixed (occasional) crash when creating via IB and providing a text field value.
5. Use placeholder color for floater when field isn't active
6. Removed some potential self captures when observing changes.