Design: Create a File class

This class will manage save files so paths don't need to be resolved in
multiple places.  I'll also use it for reading and writing with version
information.

Signed-off-by: Bryan Schumaker <bjschuma@gmail.com>

design.txt

@@ -19,12 +19,14 @@ Files:
 	ocarina/include/
 		database.h
 		database.hpp
+		file.h
 		group.h
 		index.h
 		library.h
 		playlist.h
 	ocarina/lib/
 		database.cpp
+		file.cpp
 		group.cpp
 		index.cpp
 		library.cpp
@@ -41,7 +43,7 @@ Files:
 
 
 
-On-disk files:
+On-disk files: (lib/file.cpp)
 	I use the disk to store data between sessions, this could include
 	library state and user preferences.  In theory, file formats do not
 	change often so updating between file formats should be possible.
@@ -58,6 +60,50 @@ On-disk files:
 Notation:
 	File << aaaaa << bbbbb << endl is translated into "aaaaa bbbbb\n"
 
+File version:
+	#define FILE_VERSION 4
+
+Open mode:
+	enum OpenMode {
+		OPEN_READ,
+		OPEN_WRITE,
+	}
+
+File:
+	class File {
+	private:
+		union {
+			ifstream in;
+			ofstream out;
+		} f;
+		unsigned int version;
+		OpenMode mode;
+		string filepath;
+	public:
+		File(filepath);
+		open(OpenMode);
+		const File &operator<<(File &);
+		const File &operator>>(File &);
+		getline(string &);
+	}
+
+File format:
+	File << FILE_VERSION << <OTHER_DATA>
+
+API:
+	File : File(filepath)
+		Resolve filepath to ~/.ocarina{-debug}/filepath
+	File : open(mode)
+		Open a file for either reading or writing.
+		If reading: Read in version from start of file
+		Else write version to file
+	File : operator<<()
+		Write data to out
+	File : operator>>()
+		Read data from in;
+	File : getline(string);
+		getline(f.in, string) to read an entire line
+
 
 
 Database: (lib/database.cpp)
@@ -81,16 +127,13 @@ Database: (lib/database.cpp)
 	include/database.hpp, which will be included by database.h.  Any
 	function not relying on a template can be written in lib/database.cpp.
 
-File version:
-	#define FILE_VERSION 4
-
 DatabaseEntry:
 	class DatabaseEntry { /* let database modify valid flag */
 	private:
 		bool valid;
 	public:
-		virtual istream &operator>>(istream &) = 0;
-		virtual ostream &operator<<(ostream &) = 0;
+		virtual File &operator>>(File &) = 0;
+		virtual File &operator<<(File &) = 0;
 		friend class Database;
 	};
 
@@ -101,7 +144,7 @@ Database:
 	class Database {
 	private:
 		unsigned int _size;  /* Number of valid rows */
-		string filename;
+		File filename;
 		vector<T> db;
 	public:
 		Database::Database(filename);
@@ -113,7 +156,7 @@ Database:
 		const T &operator[](unsigned int);
 	};
 
-	File << FILE_VERSION << db.size() << endl
+	File << db.size() << endl
 	File << INDEX_0 << db[INDEX_0].valid << db[INDEX_0] << endl;
 	File << Index_1 << db[INDEX_1].valid << db[INDEX_1] << endl;
 	...
@@ -144,7 +187,7 @@ Index:
 	class Index {
 	private:
 		map<string, set<int>>
-		string filename;
+		File filename;
 	public:
 		Index::Index(filename);
 		void load();
@@ -281,7 +324,8 @@ Updating algorithm:
 	happen while idle.
 
 - API
-	/* Path management */
+	library :: init();
+		Initialize all databases
 	library :: add_path(string dir);
 		Add new row to paths table, update
 	library :: del_path(unsigned int lib_id);
@@ -315,6 +359,8 @@ Default groups:
 		Tracks with a play count of 0
 
 - API
+	group :: init();
+		Initialize the index
 	group :: list();
 		return group_idx.keys();
 	group :: get_tracks(name):