(python-font-lock-keywords): Pick up block introducing keywords with

(python-font-lock-keywords): Pick up block introducing keywords with
immediately following colons.  Sjoerd noticed this one too.  Here's a
nonsense.py file that flexes all the font-lock keyword combinations.

class A:
    class B(A):
	pass
    def __init__(self):
	if i == 2 and j == 3 or k == 4:
	    import stuff
	    from otherstuff import cool
	    for i in range(cool.count):
		if i == j:
		    break
		elif j == 1:
		    continue
		print i
	    else:
		return not i
	elif q is not i:
	    return lambda x: x + 1
	else:
	    try:
		try:
		    raise stuff.error
		except stuff.error, v:
		    print v
		except:
		    global q
	    finally:
		while q > 0:
		    q = q - 1
		assert q == 0

def make():
    a = A()
    exec "nonsense"
    del a