memory can be freed while keeping a rust reference to it

[lovasoa]

https://github.com/mmghannam/russcip/blob/cdda8e7142d7bf62769eafc5cd58fd27eb305045/src/model.rs#L193-L195

Souldn't this be a Drop implementation ?

The library should not leak memory, or free memory that can still be accessed. Maybe you should add a test where you solve many large problems in a loop ?