[New Rule] Reduce conditional expressions to boolean expressions

Explanation

Sometimes conditional expressions can be replaced with boolean ones, like this:

• a if a else b -> a or b
• b if a else a -> a and b

This makes the code shorter and removes redundant evaluations of expressions. I think a check to suggest such replacements would fit well in this plugin.

Example

# Bad
x = o.x if o.x else default_x

# Good
x = o.x or default_x

[SpecLad]

b if a else a is not equivalent to b or a.

[MartinThoma]

As the ternary expressions (a if a else b) are easier for me to understand than the logical expressions (a or b), I will not implement this rule.