Fixing #1903 - metaparam inheritance is much faster

This doesn't actually fix the specific request in #1903,
which said there should be no inheritance at all, but
I've changed my mind on that. Static inheritance is good,
it should just be faster.

This change could result in up to 70% speed improvements
in compiling.

Signed-off-by: Luke Kanies <luke@puppetlabs.com>