Automated build for libxdk version v0.1

This release provides the libxdk.a static library and public headers for Linux, built with GCC 9.4.0 on Ubuntu 20.04.

Contents:

• lib/libxdk.a: The static library.
• include/xdk/: All public header files.
• samples/: Samples which show how to use the library.

See the commit history for detailed changes.