Add more expectations

[Katalam]

When merge this will:

• add .idea folder to git ignore
• add a strict check to prime expectation
• add a sum of expectation
• add a product of expectation
• add a logarithm expectation
• add an absolute expectation

[faissaloux]

@Katalam Thank you for your contribution, can you please split this PR into multiple ones where each PR would have only one purpose.

[Katalam]

#20
#21
#22
#23