Remove '-Werror' from the default make target to make it easy for
regular users of RGBDS to compile the source code. Only a few basic
warnings are left in that target.
All the warnings have been moved to a new target called 'develop'. This
target is now the one used in Travis CI to check for problems during
compilation.
Signed-off-by: Antonio Niño Díaz <antonio_nd@outlook.com>
Also, LICENSE.rst doesn't have any special formatting now, so it has
been renamed to LICENSE.
Signed-off-by: Antonio Niño Díaz <antonio_nd@outlook.com>
