Filesystem handling is now more flexible

- removed CResourceLoader class in favor of one that implements resource loader interface
- removed global pool of files, in favour of more dynamic approach
- renamed some files to match current situation
All these changes are needed mostly for future mod manager + .zip support

lib/filesystem/AdapterLoaders.h

@@ -0,0 +1,79 @@
+#pragma once
+
+/*
+ * AdapterLoaders.h, part of VCMI engine
+ *
+ * Authors: listed in file AUTHORS in main folder
+ *
+ * License: GNU General Public License v2.0 or later
+ * Full text of license available in license.txt file, in main folder
+ *
+ */
+
+#include "ISimpleResourceLoader.h"
+#include "Filesystem.h"
+
+class CFileInfo;
+class CInputStream;
+
+/**
+ * Class that implements file mapping (aka *nix symbolic links)
+ * Uses json file as input, content is map:
+ * "fileA.txt" : "fileB.txt"
+ * Note that extension is necessary, but used only to determine type
+ *
+ * fileA - file which will be replaced
+ * fileB - file which will be used as replacement
+ */
+class DLL_LINKAGE CMappedFileLoader : public ISimpleResourceLoader
+{
+public:
+	/**
+	 * Ctor.
+	 *
+	 * @param config Specifies filesystem configuration
+	 */
+	explicit CMappedFileLoader(const std::string &mountPoint, const JsonNode & config);
+
+	/// Interface implementation
+	/// @see ISimpleResourceLoader
+	std::unique_ptr<CInputStream> load(const ResourceID & resourceName) const override;
+	bool existsResource(const ResourceID & resourceName) const override;
+	std::string getMountPoint() const override;
+	boost::optional<std::string> getResourceName(const ResourceID & resourceName) const override;
+	std::unordered_set<ResourceID> getFilteredFiles(std::function<bool(const ResourceID &)> filter) const;
+
+private:
+	/** A list of files in this map
+	 * key = ResourceID for resource loader
+	 * value = ResourceID to which file this request will be redirected
+	*/
+	std::unordered_map<ResourceID, ResourceID> fileList;
+};
+
+class DLL_LINKAGE CFilesystemList : public ISimpleResourceLoader
+{
+	std::vector<std::unique_ptr<ISimpleResourceLoader> > loaders;
+
+	std::set<ISimpleResourceLoader *> writeableLoaders;
+
+public:
+	/// Interface implementation
+	/// @see ISimpleResourceLoader
+	std::unique_ptr<CInputStream> load(const ResourceID & resourceName) const override;
+	bool existsResource(const ResourceID & resourceName) const override;
+	std::string getMountPoint() const override;
+	boost::optional<std::string> getResourceName(const ResourceID & resourceName) const override;
+	std::unordered_set<ResourceID> getFilteredFiles(std::function<bool(const ResourceID &)> filter) const override;
+	bool createResource(std::string filename, bool update = false) override;
+	std::vector<const ISimpleResourceLoader *> getResourcesWithName(const ResourceID & resourceName) const override;
+
+	/**
+	 * Adds a resource loader to the loaders list
+	 * Passes loader ownership to this object
+	 *
+	 * @param loader The simple resource loader object to add
+	 * @param writeable - resource shall be treated as writeable
+	 */
+	void addLoader(ISimpleResourceLoader * loader, bool writeable);
+};