Add ui-commit.c + misc ui cleanups

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

cgit.h

@@ -92,7 +92,8 @@ extern void cgit_print_pageheader(char *title);
 extern void cgit_print_repolist(struct cacheitem *item);
 extern void cgit_print_summary();
 extern void cgit_print_log(const char *tip, int ofs, int cnt);
-extern void cgit_print_view(char *hex);
-extern void cgit_print_tree(const char *sha1);
+extern void cgit_print_view(const char *hex);
+extern void cgit_print_tree(const char *hex);
+extern void cgit_print_commit(const char *hex);
 
 #endif /* CGIT_H */