some fixes to stamper, add options for over-image stamp & alpha colors
watermark with imagine
fix : debug removed
CS
Update stamp and watermark to version 3.8
Update stamp and watermark to version 3.8
Remove dependency on convert and composite
Bump to alpha 15
Add unit tests
Fix CS
Merge pull request #461 from romainneutron/stamp-watermark

[3.8] Remove dependency on convert and composite binaries