This information is hardly going to be useful to a user of Delve and if
the user really needs information on new threads they can simply using
the provided commands to list and switch between threads.

Refactor to introduce client/server separation, including a typed
client API and a HTTP REST server implementation.

Refactor the terminal to be an API consumer.

Eliminate a race condition in TestHalt where the RequestManualStop
call can precede the Continue call, causing the test to sporadically
fail.

* Ignore signals we do not care about
* Implement custom fork/exec for Darwin to convert signals to mach
  exceptions

* Properly find next source line for goroutines blocked in chanrecv
* Refactor breakpoint clearing
* Refactor temp breakpoint setting