Added packaging functionality, added packaged exe support to filesystem

Adds package.c and package.h. Adds support for the `--pack` argument for
packing a project directory into an exe or tar file.

src/package.h

@@ -0,0 +1,19 @@
+/**
+ * Copyright (c) 2016 rxi
+ *
+ * This library is free software; you can redistribute it and/or modify it
+ * under the terms of the MIT license. See LICENSE for details.
+ */
+
+enum {
+  PACKAGE_TTAR,
+  PACKAGE_TEXE
+};
+
+enum {
+  PACKAGE_ESUCCESS =  0,
+  PACKAGE_EFAILURE = -1
+};
+
+void package_make(const char *indir, const char *outfile, const char *exefile, int type);
+int package_run(int argc, char **argv);