reduce number of meta value warnings when simulating with GHDL
update copyright to LGPL for compatibility with Xilinx modules.
This function contains code that is based on algorithms from VICE
that are available in C source under the GPL.  As we have not used
their source, but rather reimplemented their algorithms, we are
not obliged to use the GPL.  We would rather use the GPL, but the
Xilinx modules are incompatible, including the clock generator.