A new Main Tab was created for Core Build local projects based on the Main
Tab used for the classic Managed Build projects. It adds these
features:

* Option to select a different binary.
* Option to control launch pre-builds.

The default value for the binary is empty string. With empty string
the behaviour for binary selection stays the same as it was.

The project name is fixed and cannot be changed. A Core Build launch
configuration is created with the project and tied to it.

There is no option to select a build configuration, because for Core
Build projects this is selected via the LaunchBar's Launch Mode.

This change relates to eclipse-cdt#758. It affects all Core Build projects,
including CMake projects.

* Restored class CoreBuildMainTab, because it is used by others.
  Created a new class CoreBuildMainTab2.
* Initialize CMainTab2.fDontCheckProgram.