[get_turns] Fix turn operation is_collinear values for L/L and L/A.

is_collinear for the first endpoint of L is now unified and is always equal to FALSE.

Add tests of is_collinear. It is tested by passing 4th and 5th char in the expected turn string (= means collinear, + means non-collinear), e.g. "mxi=+" for L/L means that L1 ends in this IP and was collinear before meeting the Point, L2 is going "inside" intersection and wasn't collinear before.

Replace method_and_operation_replacer with turn_transformer.