Initial import Conque 2.3
Make Conque buffer restore it's state upon enter

Before the change we had two options - stay in normal mode or change to
insert mode upon enter. The behavior is driven by variable
g:ConqueTerm_InsertOnEnter. This change adds third state (denoted by
number 2) which makes the buffer remember in which state you left it and
restore the state upon entering the buffer back.