* use structs instead of interfaces
  * compiler lays out data structures ahead of time,
    so no more parsing of strings.
  * unified reflect data structures with interface
    runtime data structures.
  * richer data structures should enable reflection
    on chans and maps, but not implemented here.

R=r,iant
DELTA=1179  (1179 added, 0 deleted, 0 changed)
OCL=31107
CL=31213