Have CDB report it, pass it on to adding watches.

Introducing EngineDefault such that CDB/LLDB can use full paths
by default and gdb can use short paths.

Reviewed-by: hjk

Add commands (CDB, gdb with '\n' delimiter for multiple),
rearrange dialogs, make ignore count a spin box.

To speed up CDB, lldb. Add to dialogs, serialize.
Move breakpoint.ui into Debugger::Internal, add buddies.

Rubber-stamped-by: hjk

Reviewed-by: hjk

For Breakpoint data manipulation.

Reviewed-by: hjk

The breakpoints are now (fairly) tightly guarded by the BreakpointHandler.
Engines and Views are only supposed to refer to them by id. They also have
individual states now. The breakpoint data is split into a "user requested"
"fixed" part in BreakpointData and the engines' acknowledged data in a new
struct BreakpointResponse.

TODO: Move m_state and m_engine members to BreakpointResponse. Fix regressions
in the marker handling.

Reviewed-by: hjk