This comes from Origin, but the changes I had to do are quite large.
These files also represents many files, but I found it to be inconvenient
to keep all the originals, simply because we would end up with way too many
files: one .cc and one .hh per filter + an enveloping .hh so users could include
without knowing which filter to use.
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
b86218b2ef