Added the initial code for the gzip compression.

The game can now compress and decompress savegames. This requires the
extra dependency of boost iostreams.  configure.ac hasn't been
modified to detect this, but a FR will be filed to make that happen.

configure.ac

@@ -865,11 +865,19 @@ if test "x$lite" = "xno"; then
 
 
         CPPFLAGS=$OLD_CPPFLAGS
-	CFLAGS=$OLD_CFLAGS
+        CFLAGS=$OLD_CFLAGS
         LIBS=$OLD_LIBS
     fi
 fi
 
+#######################################################################
+# Check for boost iostreams                                           #
+#######################################################################
+
+# FIXME do a check
+
+LIBS="$LIBS -lboost_iostreams"
+
 #######################################################################
 # Tune gettext stuff for our needs                                    #
 #######################################################################

src/game.cpp

@@ -71,6 +71,10 @@
 #include <sstream>
 #include <string>
 
+#include <boost/iostreams/copy.hpp>
+#include <boost/iostreams/filtering_streambuf.hpp>
+#include <boost/iostreams/filter/gzip.hpp>
+
 #define ERR_CONFIG LOG_STREAM(err, config)
 #define WRN_CONFIG LOG_STREAM(warn, config)
 #define LOG_CONFIG LOG_STREAM(info, config)
@@ -1847,6 +1851,11 @@ static int play_game(int argc, char** argv)
 			<< "  -f, --fullscreen             runs the game in full screen mode.\n"
 			<< "  --fps                        displays the number of frames per second the game\n"
 			<< "                               is currently running at, in a corner of the screen.\n"
+			<< " --gunzip INFILE               decompresses a savefile which should be a .gz file\n" 
+			<< "                               (INFILE) and stores it without the .gz suffix.\n"
+			<< "                               The (INFILE) will be removed.\n"
+			<< " --gzip INFILE                 compresses a savefile (INFILE) as gzip file and \n"
+			<< "                               stores it as (INFILE.gz) and removes (INFILE).\n"
 			<< "  -h, --help                   prints this message and exits.\n"
 			<< "  --load SAVEGAME              loads the file SAVEGAME from the standard save\n"
 			<< "                               game directory.\n"
@@ -1924,6 +1933,9 @@ static int play_game(int argc, char** argv)
 				}
 				p = q;
 			}
+		//! @todo the (de)compress will be removed, the feature is broken for quite
+		//! a while and is replaced with --g(un)zip. 1.5.1 would be a nice point for
+		//! removal.
 		} else if(val == "--compress" || val == "--decompress") {
 			if(argc != arg+3) {
 				std::cerr << "format of " << val << " command: " << val << " <input file> <output file>\n";
@@ -1961,6 +1973,67 @@ static int play_game(int argc, char** argv)
 			}
 
 			return 0;
+
+		} else if(val == "--gzip") {
+			if(argc != arg + 2) {
+				std::cerr << "format of " << val << " command: " << val << " <input file>\n";
+				return 2;
+			}
+
+			const std::string input_file(argv[arg + 1]);
+			const std::string output_file(input_file + ".gz");
+
+			try {
+			std::ofstream ofile(output_file.c_str(), std::ios_base::out 
+					| std::ios_base::binary | std::ios_base::binary);
+
+				std::ifstream ifile(input_file.c_str(), 
+					std::ios_base::in | std::ios_base::binary);
+				boost::iostreams::filtering_streambuf<boost::iostreams::input> in;
+				in.push(boost::iostreams::gzip_compressor());
+				in.push(ifile);
+				boost::iostreams::copy(in, ofile);
+
+				ifile.close();
+				return remove(input_file.c_str());
+
+			}  catch(io_exception& e) {
+                std::cerr << "IO error: " << e.what() << "\n";
+			}
+
+		} else if(val == "--gunzip") {
+			if(argc != arg + 2) {
+				std::cerr << "format of " << val << " command: " << val << " <input file>\n";
+				return 2;
+			}
+
+			const std::string input_file(argv[arg + 1]);
+			if(input_file.substr(input_file.length() - 3) != ".gz") {
+
+				std::cerr << "file '" << input_file << "'isn't a .gz file\n";
+				return 2;
+			}
+			const std::string output_file(
+				input_file, 0, input_file.length() - 3);
+
+			try {
+				std::ofstream ofile(output_file.c_str(), std::ios_base::out 
+					| std::ios_base::binary | std::ios_base::binary);
+
+				std::ifstream ifile(input_file.c_str(), 
+					std::ios_base::in | std::ios_base::binary);
+				boost::iostreams::filtering_streambuf<boost::iostreams::input> in;
+				in.push(boost::iostreams::gzip_decompressor());
+				in.push(ifile);
+				boost::iostreams::copy(in, ofile);
+
+				ifile.close();
+				return remove(input_file.c_str());
+
+			}  catch(io_exception& e) {
+                std::cerr << "IO error: " << e.what() << "\n";
+			}
+
 		} else if(val == "--logdomains") {
 			std::cout << lg::list_logdomains() << "\n";
 			return 0;