Bug 795230 - Rename Blend tool and provide PDB compatibility

Add new PDB group "drawable_edit" which has all procedures from the
"edit" group which are not cut/copy/paste.

The new group's procedures don't have opacity, paint_mode
etc. arguments but take them from the context instead. Unlike the old
gimp-edit-fill, gimp-drawable-edit-fill now uses the context's opacity
and paint_mode.

The new gimp-drawable-edit-gradient-fill procedure uses even more
context properties which are also newly added with this commit
(gradient_color_space, gradient_repeat_mode, gradient_reverse).

And some cleanup in context.pdb.

This is still WIP, nothing in the edit group is depcreated yet.

devel-docs/libgimp/libgimp-docs.sgml

@@ -44,6 +44,7 @@
       <xi:include href="xml/gimpdisplay.xml" />
       <xi:include href="xml/gimpdrawable.xml" />
       <xi:include href="xml/gimpdrawablecolor.xml" />
+      <xi:include href="xml/gimpdrawableedit.xml" />
       <xi:include href="xml/gimpdrawabletransform.xml" />
       <xi:include href="xml/gimpedit.xml" />
       <xi:include href="xml/gimpfileops.xml" />

devel-docs/libgimp/libgimp-sections.txt

@@ -421,6 +421,16 @@ gimp_drawable_posterize
 gimp_drawable_threshold
 </SECTION>
 
+<SECTION>
+<FILE>gimpdrawableedit</FILE>
+gimp_drawable_edit_clear
+gimp_drawable_edit_fill
+gimp_drawable_edit_bucket_fill
+gimp_drawable_edit_gradient_fill
+gimp_drawable_edit_stroke_selection
+gimp_drawable_edit_stroke_item
+</SECTION>
+
 <SECTION>
 <FILE>gimpdrawabletransform</FILE>
 gimp_drawable_transform_flip_simple