Split up builtin commands into separate files from git.c

Right now it split it into "builtin-log.c" for log-related commands
("log", "show" and "whatchanged"), and "builtin-help.c" for the
informational commands (usage printing and "help" and "version").

This just makes things easier to read, I find.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

builtin-log.c

@@ -0,0 +1,69 @@
+/*
+ * Builtin "git log" and related commands (show, whatchanged)
+ *
+ * (C) Copyright 2006 Linus Torvalds
+ *		 2006 Junio Hamano
+ */
+#include "cache.h"
+#include "commit.h"
+#include "diff.h"
+#include "revision.h"
+#include "log-tree.h"
+
+static int cmd_log_wc(int argc, const char **argv, char **envp,
+		      struct rev_info *rev)
+{
+	struct commit *commit;
+
+	rev->abbrev = DEFAULT_ABBREV;
+	rev->commit_format = CMIT_FMT_DEFAULT;
+	rev->verbose_header = 1;
+	argc = setup_revisions(argc, argv, rev, "HEAD");
+
+	if (argc > 1)
+		die("unrecognized argument: %s", argv[1]);
+
+	prepare_revision_walk(rev);
+	setup_pager();
+	while ((commit = get_revision(rev)) != NULL) {
+		log_tree_commit(rev, commit);
+		free(commit->buffer);
+		commit->buffer = NULL;
+	}
+	return 0;
+}
+
+int cmd_whatchanged(int argc, const char **argv, char **envp)
+{
+	struct rev_info rev;
+
+	init_revisions(&rev);
+	rev.diff = 1;
+	rev.diffopt.recursive = 1;
+	return cmd_log_wc(argc, argv, envp, &rev);
+}
+
+int cmd_show(int argc, const char **argv, char **envp)
+{
+	struct rev_info rev;
+
+	init_revisions(&rev);
+	rev.diff = 1;
+	rev.diffopt.recursive = 1;
+	rev.combine_merges = 1;
+	rev.dense_combined_merges = 1;
+	rev.always_show_header = 1;
+	rev.ignore_merges = 0;
+	rev.no_walk = 1;
+	return cmd_log_wc(argc, argv, envp, &rev);
+}
+
+int cmd_log(int argc, const char **argv, char **envp)
+{
+	struct rev_info rev;
+
+	init_revisions(&rev);
+	rev.always_show_header = 1;
+	rev.diffopt.recursive = 1;
+	return cmd_log_wc(argc, argv, envp, &rev);
+}