Pipeline data mutability

[eyadgaran]

Changes pipeline behavior to use projected dataset splits instead of cached copies of data

[coveralls]

Pull Request Test Coverage Report for Build 1326493809

• 67 of 192 (34.9%) changed or added relevant lines in 8 files are covered.
• 8 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+1.6%) to 15.131%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
simpleml/datasets/abstract_mixin.py	0	2	0.0%
simpleml/datasets/numpy_mixin.py	0	2	0.0%
simpleml/datasets/base_dataset.py	14	17	82.35%
simpleml/pipelines/validation_split_mixins.py	7	13	53.85%
simpleml/datasets/dataset_splits.py	12	20	60.0%
simpleml/datasets/pandas_mixin.py	18	28	64.29%
simpleml/pipelines/projected_splits.py	16	35	45.71%
simpleml/utils/hash_recalculation.py	0	75	0.0%
<!--	Total:	67	192	34.9%	-->

Files with Coverage Reduction	New Missed Lines	%
simpleml/datasets/numpy_mixin.py	1	61.29%
simpleml/pipelines/validation_split_mixins.py	1	48.53%
simpleml/datasets/pandas_mixin.py	6	59.66%
<!--	Total:	8		-->

Totals
Change from base Build 1281626478:	1.6%
Covered Lines:	476
Relevant Lines:	3830

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💛 - Coveralls