Debugger: Remove unused 'precise breakpoints' setting.

Remove break window menu action to toggle 'Full path'.
Remove gdb setting 'Use full path'.
Clean up break dialog:
- Set PathChooser::ExpectedKind before value (showed up in red).
- Use PathChooser::setPath()/path() instead of lineedit text
- Return thread spec
- Add validator for ignorecount as for breakcondition.ui
Remove unused fields from breakcondition.ui

Reviewed-by: hjk
Task-number: QTCREATORBUG-2593

src/plugins/debugger/debuggeractions.cpp

@@ -333,18 +333,6 @@ DebuggerSettings *DebuggerSettings::instance()
     item->setText(tr("Synchronize Breakpoints"));
     instance->insertItem(SynchronizeBreakpoints, item);
 
-    item = new SavedAction(instance);
-    item->setText(tr("Use Precise Breakpoints"));
-    item->setToolTip(tr("Selecting this causes breakpoint synchronization "
-      "being done after each step. This results in up-to-date breakpoint "
-      "information on whether a breakpoint has been resolved after "
-      "loading shared libraries, but slows down stepping."));
-    item->setCheckable(true);
-    item->setDefaultValue(false);
-    item->setValue(false);
-    item->setSettingsKey(debugModeGroup, QLatin1String("UsePreciseBreakpoints"));
-    instance->insertItem(UsePreciseBreakpoints, item);
-
     item = new SavedAction(instance);
     item->setText(tr("Adjust Breakpoint Locations"));
     item->setToolTip(tr("Not all source code lines generate "