- use iverilog's -gstrict-expr-width throughout test suite
- add warnings for excess bits or padding zeroes in number literals
- add new --oversized-numbers parameter to retain support for unsized
  numbers wider than 32 bits
- localized use of oversized numbers to new truncate test suite which
  verifies the behavior of both modes, and compares against the known
  behavior of iverilog

- detect and forbid non-positive size casts
- detect and forbid negative struct pattern literal indices
- avoid invalid constant folding of negative based literals

- add unified frontend configuration record to make adding future
  options easier
- use ExceptT throughout, rather than using runExceptT at internal
  boundaries

Workarounds for resolved iverilog issues have been removed.

- upgrade to happy 1.20
- placate GHC warning on version fallback
- fix stack sdist failure

- support ports with sizes which depend on constant functions
- restore package item injection utility to package conversion module
- additional unbased unsized conversion test coverage

- references to other instances are no longer flagged
- special handling for genvars to avoid flagging and modport scoping
- interface inlining visits expressions in declarations
- Scoper has interface for removing entries

- don't keep unused template modules even if they are fully-specified
- don't reduce modules with unbound type parameters