Made CoefficientBuilder abstract and created concrete subclasses with
variable and fixed (maximum) filter orders
Filter coefficient producers now use abstract filter coefficients.
Added a Limits namespace for various limits
Added checks.validation for relative frequencies and also added checks
for frequencies.
Imported necessary include of simpledsp/Values.hpp
Introduced extra static_asserts for template classes and used
simpledsp/Limits.hpp for maximum number of channels.
Added a Dynamics namespace and put the Limiter and reciprocal namespaces
inside, so that class names can be shorter.
Made preparations for really doing something with multi band splitter!
Initial implementation of multiband-splitter
Initial implementation of multiband filtering