Support for forward compatibility of configurations, user and system

config bundles, project files (3MFs, AMFs). When loading these files,
the caller may decide whether to substitute some of the configuration
values the current PrusaSlicer version does not understand with
some reasonable default value, and whether to report it. If substitution
is disabled, an exception is being thrown as before this commit.
If substitution is enabled, list of substitutions is returned by the
API to be presented to the user. This allows us to introduce for example
new firmware flavor key in PrusaSlicer 2.4 while letting PrusaSlicer
2.3.2 to fall back to some default and to report it to the user.

When slicing from command line, substutions are performed by default
and reported into the console, however substitutions may be either
disabled or made silent with the new "config-compatibility" command
line option.

Substitute enums and bools only.  Allow booleans to be parsed as
    true: "1", "enabled", "on" case insensitive
    false: "0", "disabled", "off" case insensitive
This will allow us in the future for example to switch the draft_shield
boolean to an enum with the following values: "disabled" / "enabled" / "limited".

Added "enum_bitmask.hpp" - support for type safe sets of options.
See for example PresetBundle::load_configbundle(...
LoadConfigBundleAttributes flags) for an example of intended usage.

WIP: GUI for reporting the list of config substitutions needs to be
implemented by @YuSanka.

src/libslic3r/Preset.hpp

@@ -113,6 +113,9 @@ public:
         TYPE_SLA_MATERIAL,
         TYPE_PRINTER,
         TYPE_COUNT,
+        // This type is here to support PresetConfigSubstitutions for physical printers, however it does not belong to the Preset class,
+        // PhysicalPrinter class is used instead.
+        TYPE_PHYSICAL_PRINTER,
     };
 
     Type                type        = TYPE_INVALID;
@@ -251,6 +254,27 @@ enum class PresetSelectCompatibleType {
 	Always
 };
 
+// Substitutions having been performed during parsing a single configuration file.
+struct PresetConfigSubstitutions {
+    // User readable preset name.
+    std::string                             preset_name;
+    // Type of the preset (Print / Filament / Printer ...)
+    Preset::Type                            preset_type;
+    enum class Source {
+        UserFile,
+        ConfigBundle,
+    };
+    Source                                  preset_source;
+    // Source of the preset. It may be empty in case of a ConfigBundle being loaded.
+    std::string                             preset_file;
+    // What config value has been substituted with what.
+    ConfigSubstitutions                     substitutions;
+};
+
+// Substitutions having been performed during parsing a set of configuration files, for example when starting up
+// PrusaSlicer and reading the user Print / Filament / Printer profiles.
+using PresetsConfigSubstitutions = std::vector<PresetConfigSubstitutions>;
+
 // Collections of presets of the same type (one of the Print, Filament or Printer type).
 class PresetCollection
 {
@@ -280,7 +304,7 @@ public:
     void            add_default_preset(const std::vector<std::string> &keys, const Slic3r::StaticPrintConfig &defaults, const std::string &preset_name);
 
     // Load ini files of the particular type from the provided directory path.
-    void            load_presets(const std::string &dir_path, const std::string &subdir);
+    void            load_presets(const std::string &dir_path, const std::string &subdir, PresetsConfigSubstitutions& substitutions, ForwardCompatibilitySubstitutionRule rule);
 
     // Load a preset from an already parsed config file, insert it into the sorted sequence of presets
     // and select it, losing previous modifications.
@@ -692,7 +716,7 @@ public:
     const std::deque<PhysicalPrinter>& operator()() const { return m_printers; }
 
     // Load ini files of the particular type from the provided directory path.
-    void            load_printers(const std::string& dir_path, const std::string& subdir);
+    void            load_printers(const std::string& dir_path, const std::string& subdir, PresetsConfigSubstitutions& substitutions, ForwardCompatibilitySubstitutionRule rule);
     void            load_printers_from_presets(PrinterPresetCollection &printer_presets);
     // Load printer from the loaded configuration
     void            load_printer(const std::string& path, const std::string& name, DynamicPrintConfig&& config, bool select, bool save=false);