Debugger: Re-work breakpoint storage handling

The actual data is now in a TreeModel. As interface to
individual breakpoints there's a new Breakpoint class
essentially providing a checked handle.

On the user code side breakHandler()->foo(bpId) is
replaced by bp.foo().

Change-Id: I82f435bad6301fce85a1d82bf6bf39e9ddba511e
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>

src/plugins/debugger/breakpoint.h

@@ -199,7 +199,6 @@ inline void operator|=(BreakpointParts &p, BreakpointParts r)
     p = BreakpointParts(int(p) | int(r));
 }
 
-
 class BreakpointParameters
 {
 public:
@@ -257,8 +256,6 @@ public:
     int correctedLineNumber; //!< Line number as seen by gdb.
 };
 
-typedef QList<BreakpointModelId> BreakpointModelIds;
-
 inline uint qHash(const Debugger::Internal::BreakpointModelId &id)
 {
     return id.toInternalId();