Avoid match error in isSatWithAssertWhileSat

[Tony Sloane]

In isSatWithAssertWhileSat the terms are passed as a Seq but matched as a list using Nil and ::, so if you pass another kind of Seq such as a Vector it crashes with a match error:

xb match {
   case Nil ⇒ ( result, count )
   case ( first, c ) :: l ⇒
       |= ( first ) match {

I wouldn’t like to change the interface to just take a list since it’s convenient to be able to pass in other things.

[Tony Sloane]

Use Seq matching instead of List

Fixes #34

→ <<cset cc54b5ce8252>>