Batcher 1.0-RC1 Released

New major feature: Batch conversion of files. You can now batch-process image files and convert them to a different file format, optionally applying procedures (scale, insert background, …) and filtering the list of images to be processed via constraints (filenames having a particular file extension, beginning/ending with a prefix/suffix, …).

Changes to procedures and constraints:

Added a new procedure named Align and offset that allows aligning layer(s) with the image or another layer. You may also apply offsets with pixels or a percentage of image/layer width/height.
For the Scale procedure, you may now choose whether to scale a layer (the default for Export Layers and Edit Layers) or the entire image (a new option, the default for Batch Convert).
Renamed Use layer size to Resize to layer size and allowed customizing the layer. You may now resize the background layer, foreground layer or all layers (the latter effectively resizing the image to fit all layers).
Added Merge filters as a built-in procedure that merges all visible filters (layer effects) in the specified layer. This is equivalent to adding the gimp-drawable-merge-filters procedure, only more convenient.
Added a new constraint named Matching text... that allows filtering items that start with, contain or end with the specified text. You may also specify a Python regular expression or perform case-insensitive matching. The name of the constraint automatically changes as you adjust its options.
The Use file extension in layer name option for the Export procedure now uses the original layer name. This way, you no longer need to specify the [full layer name] field just to preserve the file extension. This also allows using different name patterns that do not include the layer name (such as image[001]).
Procedures and constraints causing errors are now automatically deactivated. This avoids spamming the user with warning dialogs.

User interface changes:

Replaced the placeholder icon in the image preview when there is no selection.
Labels describing procedure/constraint parameters are now insensitive (grayed out) if their corresponding GUI elements are insensitive.
Export settings are now insensitive while exporting.

Other changes: