Sd-mecha

- add SD 3.5 config

- allow to merge in delta space by passing `strict_weight_space=False` in `RecipeMerger.merge_and_save()`
- handle unexpected float types when expecting an integer in some merge methods
- replace the parameter `no_rescale` of the method `ties_sum_with_dropout` with `rescale` and use a differentiable implementation
- use `torch.Generator` instead of `torch.manual_seed`
- revert the use of `torch.svd_lowrank` in rotate when alignment is fractional, otherwise it results in nans during inference

- fix a bug where the model configurations would silently fail to parse
- fix none seed not supported as a default hyper value

- remove CWM (`sd_mecha.hypers.classes`)

- speedup `rotate` method by ~2x using `torch.svd_lowrank`

- add new builtin methods: `n_average`, `geometric_median`, `ties_sum_extended` / `add_difference_ties_extended`, `ties_sum_with_dropout` / `ties_with_dare`, `model_stock_for_tensor` / `model_stock_n_models`
- add a new parameter `vote_sgn` to `ties_sum` / `add_differenc_ties`

credits to 6DammK9 for this contribution!