The compilation unit scope is now treated as a specialised form of
package (with an automatically generated name). All items declared
outside a design element are added to the current compilation unit
package. Apart from when searching for a symbol, once we get into
elaboration we can treat these just like any other package.
Emit the elaborated class methods. Also generate root scopes to
represent the classes in order to hold the methods. These scopes
can also in the future be used to implement static properties.
The disciplines are, from the perspective of the ivl target, collected
into the design. Add functions for the target to scan the disciplines
in the design.
In the process, also clean up the handlng of design constants.
In the ivl_target API, the IVL_EX_BACCESS expression type gets some meat,
specifically references to the branch it accesses and the the nature to
be accessed on that branch.
This includes enough API to get the branch nexus bits and signals
and show them in the dump. This also includes creating the reference
ground for branch access functions that use the implicit ground.
NetTran devices must be collected into islands because they are all
a bi-directional mass. This is how vvp will process them and the code
generator will need a head start organizing them.