some more functionality for miscLib

tactics to split the p in terms that arise from
  let (x,y,...) = p in ...
or
  case p of (x,y,...) => ...

more particularly, adds an assumption
  p = (x,y,z,...)
for some new variables x,y,z,...

also, a function for sorting a list of variables by their names
some more theorems about the clock

at the dec and decs levels