Naive implementation of getting a callgraph.

Using recursion is probably a bad idea, but it will help with
prototyping and building out the UI.
Merge remote-tracking branch 'origin/get-callgraph' into view-callgraph

Conflicts:
	web/Xhgui/Profile.php
Fix notice error.
Trim wrapping array off.

It makes rendering the chart harder.
Initial pass at implementing a very basic callgraph tree.

Basically copied from the d3.js examples, but it is a start, the current
code hits PHP memory limits pretty easily as json_encoding the callgraph
can easily exhaust all the memory allocated to PHP.
Exclude functions that are less that 1% of the total run time.

Functions that less than 1% of the runtime will just add noise to the
graph and make reading data harder.
Remove stray </li>
Make chart a bit more readable.
Fix incorrect time display.
Add % values to each node in the callgraph.

These values can be used to generate circles of various sizes in the
callgraph.