Add Rf100 peixos segmentation dataset

[cregouby]

Fix #234

and also

• refactor coco_dataset for better inheritance
• fix dataset_lfw double / in URL
• separate transform_ in documentation

[cregouby]

windows untar leads to

 home/zuppif/Documents/Work/RoboFlow/ODinW-RF100-challenge/rf100/peixos-fish/test/_annotations.coco.json: Can't create '\\\\?\\C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\RtmpaYCTbC\\working_dir\\RtmpoljjKw\\filedd45aea47d5\\rf100_peixos_segmentation_dataset\\home\\zuppif\\Documents\\Work\\RoboFlow\\ODinW-RF100-challenge\\rf100\\peixos-fish\\test\\_annotations.coco.json': No such file or directory
home/zuppif/Documents/Work/RoboFlow/ODinW-RF100-challenge/rf100/peixos-fish/train/_annotations.coco.json: Can't create '\\\\?\\C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\RtmpaYCTbC\\working_dir\\RtmpoljjKw\\filedd45aea47d5\\rf100_peixos_segmentation_dataset\\home\\zuppif\\Documents\\Work\\RoboFlow\\ODinW-RF100-challenge\\rf100\\peixos-fish\\train\\_annotations.coco.json': No such file or directory
home/zuppif/Documents/Work/RoboFlow/ODinW-RF100-challenge/rf100/peixos-fish/valid/_annotations.coco.json: Can't create '\\\\?\\C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\RtmpaYCTbC\\working_dir\\RtmpoljjKw\\filedd45aea47d5\\rf100_peixos_segmentation_dataset\\home\\zuppif\\Documents\\Work\\RoboFlow\\ODinW-RF100-challenge\\rf100\\peixos-fish\\valid\\_annotations.coco.json': No such file or directory
tar.exe: Error exit delayed from previous errors.
home/zuppif/Documents/Work/RoboFlow/ODinW-RF100-challenge/rf100/peixos-fish/test/_annotations.coco.json: Can't create '\\\\?\\C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\RtmpaYCTbC\\working_dir\\RtmpoljjKw\\filedd45aea47d5\\rf100_peixos_segmentation_dataset\\home\\zuppif\\Documents\\Work\\RoboFlow\\ODinW-RF100-challenge\\rf100\\peixos-fish\\test\\_annotations.coco.json': No such file or directory
home/zuppif/Documents/Work/RoboFlow/ODinW-RF100-challenge/rf100/peixos-fish/train/_annotations.coco.json: Can't create '\\\\?\\C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\RtmpaYCTbC\\working_dir\\RtmpoljjKw\\filedd45aea47d5\\rf100_peixos_segmentation_dataset\\home\\zuppif\\Documents\\Work\\RoboFlow\\ODinW-RF100-challenge\\rf100\\peixos-fish\\train\\_annotations.coco.json': No such file or directory
home/zuppif/Documents/Work/RoboFlow/ODinW-RF100-challenge/rf100/peixos-fish/valid/_annotations.coco.json: Can't create '\\\\?\\C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\RtmpaYCTbC\\working_dir\\RtmpoljjKw\\filedd45aea47d5\\rf100_peixos_segmentation_dataset\\home\\zuppif\\Documents\\Work\\RoboFlow\\ODinW-RF100-challenge\\rf100\\peixos-fish\\valid\\_annotations.coco.json': No such file or directory
tar.exe: Error exit delayed from previous errors.