restructure into smaller files & add IWYU/clang-tidy

Signed-off-by: Folling <mail@folling.io>

include/ikarus/objects/property.h

@@ -0,0 +1,73 @@
+#pragma once
+
+// IMPLEMENTATION_DETAIL_LAZY_VALUE_CREATION, IMPLEMENTATION_DETAIL_PROPERTY_TYPES
+
+/// \file property.h
+/// \author Folling <mail@folling.io>
+
+#include <ikarus/id.h>
+#include <ikarus/macros.h>
+#include <ikarus/objects/blueprint.h>
+#include <ikarus/objects/entity.h>
+
+/// \defgroup properties Properties
+/// \brief Properties define the structure and types of data.
+
+IKARUS_BEGIN_HEADER
+
+/// \brief Properties are the placeholders of values for entities.
+/// \details Each entity can have any number of properties.
+/// Every property has a type that identifies the kind of data that can be put in.
+///
+/// The following types currently exist:
+/// - Toggle: A true/false boolean-like value
+/// - Number: An arbitrary numeric value
+/// - Text: An arbitrary textual value
+///
+/// Property Examples:
+/// - Is Dead (Toggle)
+/// - Age (Number)
+/// - ISBN (Text)
+///
+/// Every property has settings which can be used to customise the property further.
+/// Two settings that are shared among all properties are the following:
+/// - Multiple
+/// - Allow undefined
+///
+/// The former transforms a property into a list. Instead of one number, you could then specify a series of numbers.
+/// The latter allows you to specify an "unknown" value for a property.
+/// It might not be known if a character is dead or not for example.
+///
+/// Each entity associated with the property has a value for it.
+///
+/// Properties can also be added to blueprints in which case they are available for all entities associated with the
+/// blueprint.
+///
+/// We call properties within entities "Entity Properties" and properties within blueprints "Blueprint Properties".
+///
+/// \remark Properties are scoped to the blueprint or entity they are associated with.
+/// \remark Values for properties are lazily created as space saving measure.
+/// Fetching the value for some property of some entity will return the property's default value if none is specified.
+/// This default value is specified when the property is created and can be updated later.
+/// \remark Properties' tree structures are scoped to the entity or blueprint they are associated with.
+struct IkarusProperty {
+    /// \private \brief The id of the property.
+    IkarusId id;
+};
+
+/// \brief The type of a property.
+/// \details Designates the type of data stored by the property as well as which settings are
+/// available.
+/// \see IkarusPropertySettings
+enum IkarusPropertyType {
+    /// \brief A true/false boolean-like value.
+    IkarusPropertyType_Toggle,
+    /// \brief An arbitrary numeric value.
+    IkarusPropertyType_Number,
+    /// \brief An arbitrary textual value.
+    IkarusPropertyType_Text,
+};
+
+IKARUS_END_HEADER
+
+// @}