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/gdb/gdboptionspage.cpp

@@ -83,8 +83,6 @@ QWidget *GdbOptionsPage::createPage(QWidget *parent)
         m_ui.environmentEdit);
     m_group.insert(theDebuggerAction(AdjustBreakpointLocations),
         m_ui.checkBoxAdjustBreakpointLocations);
-    m_group.insert(theDebuggerAction(UsePreciseBreakpoints),
-        m_ui.checkBoxUsePreciseBreakpoints);
     m_group.insert(theDebuggerAction(GdbWatchdogTimeout),
         m_ui.spinBoxGdbWatchdogTimeout);