[Patch] Add/modify regex comments

[Jonathan Wakely]

On 14/03/14 14:55 -0400, Tim Shen wrote:
>Fix some inaccurate comments, especially the asymptotic complexity
>mark: o() => \Omega().

If all the tests pass this is OK for trunk, thanks.

N.B. the patch is fine but I don't think we usually say

   @brief Class FooBar. Does some Foo and some Bar.

just

   @brief Does some Foo and some Bar.

Because Doxygen always outputs the class details anyway.