highlighting problems / period is not everything

[murphy]

hi why and list!

the new syntax highlighting surely brought more colors to the guide, but also a 
few problems.

some boxes shouldn't get highlighted, namely shell input like in The Tiger's Vest:

	ri Enumerable#zip

or some irb result output like in chapter 6:

	irb> NameCaller.new.simon( 'Hello?', 'Hello? Simon?' )
	You're calling `simon' and you say:
	  Hello?
	  Hello? Simon?
	But no one is there yet.

is highlighted with a string 're calling `simon'.

also, it seems that Syntax doesn't get o.class, also in The Tiger's Vest:
	
	42.class      42.instance_eval ...

is highlighted like a class definition.


another thing in chapter 6, in the section about character classes:

	. the period matches everything.

everything _but_ a newline. you should mention that, I think.
it's one of the pitfalls that confuse beginners.
and then, you should also introduce the /m modifier.

the cartoons in #6 are great!
[murphy]