Make placeholders presents only in theme

[noirbizarre]

Detailed Description

Placeholders are split between themes and core. It should be consistent and I propose to make it a themable element (so to put them in the themes).

Context

When customizing uData , I want to make the placeholders consistent with my theme.
When coding on uData , I don't want to search and ask questions on how placeholders are handled.

Possible Implementation

Make the placeholders a themable element. Optionnaly provide a fallback on core mecanism.

Your Environment

Version 1.0