Benchmark of the strokes

[LukasT.dev@gmail.com]

Hi, 

I commited benchmark for strokes and I did first test today with callgrind  
backend [1] from Qt 4.6. It took almost 15 minutes but then I break it.

The stroke benchmars looks like [2] and [3]. Thanks to the settings 
serialization we can test any paintop. I did test for Pixel Brush, autobrush 
with radius of 70 px.

I run it like ./KisStrokeBenchmark -iterations 10 -callgrind

All benchmarks now passed and do not crash.

Lukas

[1] http://lukast.mediablog.sk/callgrind/callgrind-stroke-benchmark.tar.gz
[2] http://imagebin.ca/view/gci4txZ4.html
[3] http://imagebin.ca/view/rokJ8H1P.html