files. Log messages added to memoize functions.

function.

good measure. More work to be done.

and allows caller to specify which arguments to use.

   values in said cache.

2. So I created new memoize decorators skipUnchanged and Instanceify to
   implement the setter value cache.

3. And discovered that, for colour map changes, canvases were only being
   redrawn because the GLSLShader value cache was broken.

function.