Make the libslic3r Headers Compile on Their Own

Each now includes, or forward-declares, what it uses instead of relying on what its includers happened to include first. Left out: I18N.hpp, which errors on purpose when included from GUI code, and VoxelizeCSGMesh.hpp and SLA/bicubic.h, which nothing includes and which no longer compile at all.

src/libslic3r/GCode/AdaptivePAProcessor.hpp

@@ -11,12 +11,14 @@
 #include <regex>
 #include <memory>
 #include <map>
+#include <unordered_map>
 #include "AdaptivePAInterpolator.hpp"
 
 namespace Slic3r {
 
 // Forward declaration of GCode class
 class GCode;
+class PrintConfig;
 
 /**
  * @brief Class for processing G-code layers with adaptive pressure advance.