There is an indentation error in the Dissolve.py script that writes out the intermediate object on every merge with an input feature rather than just once at the end of the processing. This results in very large output file sizes.

I have also edited the defineCharacteristics function to allow the tool input to accept polyline features as well as polygons, in line with the fTools UI.
[processing] fix Distance Matrix tool (fix #7618)
[processing] fix wrong tools description (fix #9852)
[processing] fix old API calls in Extract by location tool (fix #9603)
[processing] better handling of non-ASCII characters in config dialog
(addresses #9323)
[FEATURE] (Processing) Eliminate with smallest polygon
[processing]Fix "float division by zero" in polygonize algorithm if no
polygons were created.
For shapely 1.2.16+ and GEOS 3.2+ unary_union will be used for noding
lines - union method sometimes failed to create properly noded polyline.
[processing] fix output names for some SAGA algorithms (fix #9789)
[processing] fix Unique values tool (fix #9870)
Fixed bug in the processing toolbox qgis:intersection tool, preventing
attempts at writing the wrong geometry type to a shapefile.
[processing] add feature count to Statistics by categories output (fix #9871)
[processing] fix MMQGIS Extract by attribute (fix #9768)
[processing] restore Create new model tool in toolbox (fix #9847)
[processing] make script editor, modeler and results viewer non modal
(fix #9849)
[processing] Allow choice of geometry column name, change database connection name to combo box for Import into PostGIS algorithm
[processing] Add option for converting field names to lowercase for Import to PostGIS algorithm
set droplists if parameter values are already set
as a result you can set some parameters in
checkBeforeOpeningParametersDialog and they will be the default in the
interface. This is especially usefull when your algo as a lot of
parameters that you can gues (eg from layer names)
Ported 'Join by location' from fTools to Processing
'Join by location' can now use the geometry from the joined layer as output.
'Join by location' now creates multipart features in the same way as SinglePartsToMultiparts.