Mutator for numbers

[Liam-Rougoor]

Is your feature request related to a problem? Please describe.
Similar to the StringMutator, we could mutate numbers.

Describe the solution you'd like
I'd like to see a mutator for numbers. Example mutations could be:

Original	Mutation
var x = 10;	var x = 0;
var x = 10;	var x = -10;

With semantic model, we could add some mutations on numeric variables as well:

Original	Mutation
var x = myNumericVariable;	var x = -myNumericVariable;

This example might be bad if myNumericVariable equals 0..

[richardwerkman]

That mutation on numeric variables is less useful, and prone to unkillable mutants. But the first ones we could definitely add.