Add elephant foot compensation to SLA print

Work in progress


Convert efc input to the right scaling


Apply EFC on the slice index to make it visible in the preview.

src/libslic3r/SLAPrint.cpp

@@ -785,6 +785,7 @@ bool SLAPrint::invalidate_state_by_config_options(const std::vector<t_config_opt
         "material_correction",
         "relative_correction",
         "absolute_correction",
+        "elefant_foot_compensation",
         "gamma_correction"
     };