Changes --moreJoins from a boolean option that is either completely off or joins everything to an integer option that has two steps:

• 1 joins all branches resulting from impure conditionals immediately (this is very similar to --conditionalizePermissions but doesn't have to be conservative and can thus join all such branches)
• 2 joins all impure branches immediately and joins branches in the CFG when possible
• 0 is off.

Similarly, the @moreJoins annotation can be used in the following ways:

• @moreJoins() selects level 2
• @moreJoins("n") selects level n
• everything else is invalid and results in a warning.