py3: make all tests pass

[chapoton]

This ticket is used to keep track of the progress towards python3.

release	files having failing doctests	more than 100	from 10 to 100	from 1 to 10	failing doctests
8.4.b3	915	42	251	622	17972
8.4.b4	803	23	175	605	10921
8.4.b5	657	17	145	495	8509
8.4.b6	594	17	127	450	7706
8.4.b7	587	17	128	442	7678
8.4.rc0	524	16	119	389	6976

Folders where all tests pass (8.4.b6):

• algebras/steenrod #26219 and #26220
• arith #26208 ✔
• combinat/sf (#26220 +) #26215
• docs ✔ #26310
• features ✔
• finance #26213 ✔
• games ✔
• gsl
• knots ✔
• lfunctions ✔
• logic #26214 ✔
• media ✔
• monoids ✔ #26294
• parallel ✔
• probability #26216 ✔
• quadratic_forms/ #26224 ✔
• quivers #26211 ✔
• server ✔
• stats #26401 ✔
• typeset ✔

Folders with work in progress:

• doc/en #26346
• algebras #26316 #26399
• combinat/species #26328
• combinat/words #26362, #26458 #26473
• crypto #26398
• data_structures #24852
• functions #24758
• game_theory #26429
• graphs #26431 #26447
• groups/matrix_gps #26400
• interfaces #26314
• libs #24804
• matrix/ #26236 (very partial fix)
• misc #26312, #26390
• modular #26382
• modules #26276
• numerical/backends #24740 (for char * arguments management) and #24741
• plot #26210 (partial fix only) #26299 #26301 #26321
• rings/number_field #26263 (partial fix only)
• sandpiles #26016
• structure #25694
• tensor #26295

[embray]

Hadn't even seen this ticket; very nice.