* interrupts: Less pessimistic synchronization for the different interrupt types. There are some issues with the interrupt number assignments.
* interrupts: Allow an option to NOT synchronize all the external interrupts coming into PLIC
* interrupts: ExampleRocketChipTop uses PeripheryAsyncExtInterrupts. Realized 'abstract' doesn't do what I thought in Scala.
* interrupts: use consistent async/periph/core ordering
* interrupts: Properly condition on 0 External interrupts
* interrupts: CLINT is also synchronous to periph clock
1. Bundles be created after base class Module constructor runs
2. Bundles must be created before Module(...) runs
Solution: pass a bundle constructor to the cake base class
Require the constructor to take a parameter so people don't use it by
accident; they should get a type error.
Consistently name all the cake arguments with an _io, _coreplex, _outer,
so that they don't shadow the base class variables you should be using.
This would allow, for instance, putting the coreplex on a separate clock
domain and crossing the IOs over through asynchronous queues.
The ExampleMultiClockTop* classes are removed since they no longer fit
into the class hierarchy.