WIP: Moved sources int src/, separated most of the source code from Perl.

The XS was left only for the unit / integration tests, and it links
libslic3r only. No wxWidgets are allowed to be used from Perl starting
from now.

src/slic3r/GUI/ConfigExceptions.hpp

@@ -0,0 +1,15 @@
+#include <exception> 
+namespace Slic3r {
+
+class ConfigError : public std::runtime_error { 
+using std::runtime_error::runtime_error;
+};
+
+namespace GUI {
+
+class ConfigGUITypeError : public ConfigError { 
+using ConfigError::ConfigError;
+};
+}
+
+}