Yosys does support some asserts nowadays. Allowing sv2v to not strip
them out means that you can check formal properties without needing
hierarchical references (which Yosys really doesn't cope well with!)

- dimensions flattening conversion only flattens packed dimensions
- conversion for packing arrays when necessary (preserves memories)
- added coverage for array with multiple packed dimensions
- test runner no longer forbids multi-dim accesses after conversion
- Decl and subordinate types derive Ord

- NestTF refactored to cover all package items
- fixed issue where type traverse skipped typedefs

This also entailed further fleshing out the expression traversal helper
to cover expressions in generate blocks, which could, of course, use
$bits.

- convert default pattern used to fill a vector
- convert Logic in parameter and localparam types
- interface conversion should happen early for type resolution later on
- interface conversion handles renaming of usages of inlined decls