Renamed some classes

[DurieuxPol]

Renamed a few classes for better clarity.
Renamed MutantEvaluationStrategy to TestSelectionStrategy, and all subclasses, and MutationsGenerationStrategy to MutantSelectionStrategy, and all subclasses.
For consistency, I also renamed RandomMutantSelection to RandomMutantSelectionStrategy.

[coveralls]

Pull Request Test Coverage Report for Build 7048838474

• 88 of 123 (71.54%) changed or added relevant lines in 24 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 60.249%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/MuTalk-Model/PercentRandomMutantSelectionStrategy.class.st	4	5	80.0%
src/MuTalk-CI/MutalkCI.class.st	0	2	0.0%
src/MuTalk-Model/MutantSelectionStrategy.class.st	2	4	50.0%
src/MuTalk-Model/StubbornOnlyMutantSelectionStrategy.class.st	0	2	0.0%
src/MuTalk-Model/TestSelectionStrategy.class.st	0	3	0.0%
src/MuTalk-Model/RandomMutantSelectionStrategy.class.st	6	13	46.15%
src/MuTalk-Model/ManualMutantSelectionStrategy.class.st	0	8	0.0%
src/MuTalk-Model/RandomOperatorMutantSelectionStrategy.class.st	11	21	52.38%

Totals
Change from base Build 6967212864:	0.0%
Covered Lines:	3774
Relevant Lines:	6264

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💛 - Coveralls

[guillep]

Thanks @DurieuxPol! This makes the code a lot clearer!