ENH: modify the start pos of wall for wipe tower

and modify the overlap of wall and infill for wipe tower
jira:none

Change-Id: I0d1355c718e2bd1efea6d898f793f5869476ab12
(cherry picked from commit 4db196b11f052d6a7a7c7a8aafe0d2b34a7d2d80)

src/libslic3r/GCode/WipeTower.hpp

@@ -304,7 +304,7 @@ private:
     float  m_travel_speed       = 0.f;
     float  m_first_layer_speed  = 0.f;
     size_t m_first_layer_idx    = size_t(-1);
-
+    size_t m_cur_layer_id;
 	// G-code generator parameters.
     float           m_cooling_tube_retraction   = 0.f;
     float           m_cooling_tube_length       = 0.f;