Vleidel tests

[bvenn]

Please list the changes introduced in this PR

• add unit test for one sample t test
• add unit test for two sample t test
• add unit test for paired two sample t test
• add unit tests for sturges and rice rule

[Required] please make sure you checked that

• [x] The project builds without problems on your machine

[Optional]

• [x] Added unit tests regarding the added features