Move the watermark module files to their new homes (rename-only commit).

--HG--
rename : modules/watermark/controllers/admin_watermarks.php => modules/watermark/classes/Watermark/Controller/Admin/Watermarks.php
rename : modules/watermark/helpers/watermark_event.php => modules/watermark/classes/Watermark/Hook/WatermarkEvent.php
rename : modules/watermark/helpers/watermark_installer.php => modules/watermark/classes/Watermark/Hook/WatermarkInstaller.php
rename : modules/watermark/helpers/watermark.php => modules/watermark/classes/Watermark/Watermark.php
rename : modules/watermark/views/admin_watermarks.html.php => modules/watermark/views/admin/watermarks.html.php
Fix the watermark module class declarations.
Add the watermark module transparent-extension-enabling files.
Search and replace in watermark module (99 places).
Merge pull request #244 from shadlaws/k3_watermark_module_translate

K3 watermark module translation.