Not compiling under Linux

[DaPeace]

Hello, only a short info, the files in visu3D are uppercase and when compiling under Linux (in my case Ubuntu), it does not find them because its searching for lowercase.
Next problem under Linux is, that in mainwindow.h the path to visu3D is with windows-like backslash so linux doestn find the viewer3D.h
Must be #include "visu3D/viewer3D.h" do work with Linux.
Then everything is compiling but i get a segmentation fault when starting.
The original GRBLHome-Branch is compiling and running fine.

Thanks for the improvements :-)