Dev-0.18.0 20250128

[shnarazk]

• reorganize primitive types 20250202 refactor primitive types #288
• move vars from AssignStack to ClauseDB or static mut ❗ static mut VAR_VECTOR: Vec<Var> #289
• move out heap of AssignStack pub static mut VAR_ACTIVITY_MANAGER: VarActivityManager #290
• use BinaryHeap for heap -- Cancelled: we need to assure uniqueness of inserted values
• use FxHash*
• ditch the old-style progress report used by C++ implementations
• try watch literal heap
• Rust 2024 edition
• change the type of clause.lits from Vec<Lit> to Vec<(&Var<'a>, bool)> 20250209 bounded static var refs #291