Create doc of ST_Accum
Update and add image ST_Accum
Update image ST_Accum
Update ST_Accum
Correction of ST_Accum
Update ST_accum
Update link of ST_Explode in ST_Accum
Add link of ST_Accum
Improve ST_Accum
Merge branch '141' into gh-pages

Create doc and image of ST_Accum