Graphviz dependency in Umbrello

[Jonathan Riddell]

I've added an autolayout feature for Umbrello's diagrams which uses
graphviz.

Not being a buildsystem expert I'd appreciate it if someone could
review the changes I made.  

kdesdk/umbrello/configure.in.in now checks for dot.h

kdesdk/umbrello/umbrello/Makefile.am now has -I/usr/include/graphviz/
as an include

and kdesdk/umbrello/umbrello/autolayout/Makefile.am has
-L/usr/lib/graphviz

I suspect there must be a better way to do the last two than static
paths.

Jonathan Riddell