Clay strips was using it's own brush local matrix,
which wasn't quite compatible with texture matrices.
This could lead to brush textures not lining up with
the stroke dabs.
There was also a bug where the stroke was starting
20 pixels into the stroke, which is much higher than
necassary to derive the initial rake angle.
Notes:
* The clay strips brush now uses SCULPT_cube_tip_init
to calculate the local brush matrix.
* SCULPT_cube_tip_init now accepts custom brush location
and radius arguments.
* The mouse sample preroll used to calculate initial brush
rotation angle is now smaller than the update interval.
* Clay strips now supports tip_scale_x, which has also
been added to DNA defaults.
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