Make the changeGrid function behave like a call-by-value function

Because of the handle functions, the changeGrid function changes the grid of the original quantity object. This is very unecpected, for me it is more common to see an object with a changed grid as a new object. Thus, I recommend to change the behaviour of this function to generate new objects.

added 2 commits

• 01053b78 - Added new input argument to automatically remove empty entries
• 606ec16c - Allow the grid to be changed allow differentiation of constant values

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added 1 commit

• cca9aa78 - Changed implementation of integration for "Discretes". The input arguments are...

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added 1 commit

• 532e6554 - fixed output of atIndex()

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merged