Add while and until expressions

[troyhen]

The following code needs to work:

while a < 0 do a = addOne
a = addOne while a < 0

while a > 0
    println "too high"
    a -= 1

until b == 1 do tryAgain()
tryAgain() until b == 1

until ready()
    send "not ready"
    try += 1
end until # end is optional, until keyword is also optional, but must match when used

while a < 0 do a += 1 else println "ready"
while a < 0 do a += 1 else println "ready" end
while a < 0 do a += 1 else println "ready" end while

while a < 0 do a += 1
else println "ready"

while a < 0
    a += 1
else println "ready"

while a < 0 do a += 1
else
    println "ready"

while a < 0
    a += 1
    println "not ready"
else
    println "ready"

until a > 0 do a += 1 else println "ready"

[troyhen]

Done