Fix CMake double precision builds

[dgcole]

Double precision builds with CMake are currently broken. Since I'm contributing the fix directly I did not bother to make an issue first, but please let me know if that is required.

The binding_generator_generate_bindings function has erroneous commas after some of its arguments (i.e., PRECISION,), but this is not correct CMake syntax; the arguments should be separated by whitespace. This causes the USE_TEMPLATE_GET_NODE, BITS, and PRECISION arguments to not be properly received when this function is invoked. This is partially masked for the BITS argument as there is a BITS variable at a higher CMake scope that is used.

The end result is that the PYTHON_SCRIPT always ends up getting populated with precision='' and use_template_get_node='', which makes it impossible to get a working double precision build via CMake.

[enetheru]

I approve these changes.

[paddy-exe]

Makes sense in terms of how CMake works👍🏻 haven't tested the changes though