0030364: Visualization, TKOpenGl - allow initializing a Surface-less EGL context

0030364: Visualization, TKOpenGl - allow initializing a Surface-less EGL context

OpenGl_Context::MakeCurrent()/OpenGl_Context::IsCurrent() have been modified to NOT fail
in case if myWindow is EGL_NO_SURFACE (valid off-screen rendering case within EGL).
OpenGl_GraphicDriver::InitEglContext() now finds EGL surface config in case if it has not been passed by argument.

OpenGl_Window constructor now allows wrapping an off-screen rendering surface EGL_NO_SURFACE.
However, it still creates a dummy surface eglCreatePbufferSurface() to workaround bugs in some GLES drivers (Vivante GC2000).

V3d_View::SetWindow()/V3d_View::MustBeResized()/V3d_Viewer::SetViewOn() have been modified
to avoid implicit View redraw (leading to undefined behavior/crashes in case if rendering
should be done into default FBO defined right after V3d_View initialization).