Reviewed-by: hjk

Add combo box listing toolchains with debuggers to start external,
attach and core.
Another attempt at streamlining engine detection:
Split in detection functions that first collect a list of
available engines by preference, then remove disabled and
wrongly configured engines and use the remaining best.
matching. checkconfiguration is now the central place where
engine detection and config check takes place.

Rubber-stamped-by: hjk

Setting up the debugger connection might fail for a couple of reasons.
Check the application output to show the user a more detailed error
message.

Reviewed-by: hjk

Move tooltip-request handling from DebuggerPlugin into
DebuggerToolTipManager.

Request tooltip only if position changed and close
standard tooltip on success.

Replace old debugger tooltip by a new ToolTipManager which
has a list of AbstractDebuggerToolTipWidget with the functionality
to 'acquire' an engine (display its data) and 'release' it
(store engine data and display them as 'previous') and serialization
to XML session data.
DebuggerTreeViewToolTipWidget implements AbstractDebuggerToolTipWidget
for tree model acting as  a filter on watch models.

Rubber-stamped-by: hjk

reviewed-by: hjk

This still needs a lot of work and sanitizing.

Use virtual function instead of if/qobject_cast cascades.

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:  Kai Koehne, Andre Poenitz

Reviewed by:  Kai Koehne, Andre Poenitz

assignValueInDebugger: Pass on WatchData as well, pass
on values as QVariant. Based on that, do more extensive
checks in CDB, preventing assignment of non-PODs.

Locals/Watch editing:
* Disable while running
* Edit pointer values as hex with validation.

CDB: Strip class types off reported pointer values and reformat
the values as short 0x-pointer values, introduce flag to
WatchData::source to do dumper expansion handling.

Windows: recognize int64 as int.

Register handler: Fix accessing uninitialized value.

namespace (from Debugger::Internal) as they are exported classes.
Introduce private classes to avoid exposing private JS debugger
headers.

Reviewed-by: Lasse Holmstedt

Saves lots of conversion.

Finally.

A new debugger engine, QmlCppEngine, is introduced, which wraps gdb
and qml engines into one. Alternatively, if using Windows, Cdb is used
instead of Gdb.

Most of the debugger ui switcher is now rewritten, and it is tailored
for the QML and CPP layout case, the only one supported anyway.

Reviewed-by: hjk