Fix image path in custom/create to use URL generation helpers.

Fixes #105
Add how to profile CLI scripts to README.
Rename 'head' to 'new' as I think it is clearer.

* After not using xhgui for a while I was totally confused by base/head.
  Using new made understanding it simpler.
* Update the links in the list to the 'new' side of the comparison as
  that is generally more useful.
* Add reminder text to the diff to help reduce confusion.
Add note about missing watch functions.
Rename Exclusive to Self.

I've always found exclusive to be a bit confusing of a term. I find self
is a much simpler term that also shows up on other profiling tools both
in browser and in places like xdebug/KCachegrind.
Add a very basic/simple client side search through functions.

It isn't elegant or super fast, but it works.

Refs #64
Merge pull request #109 from perftools/rename-exclusive

Rename exclusive to self
Merge pull request #110 from perftools/client-side-filter

Add a very basic/simple client side search through functions.