Fixed issue with bezier curve

Fixed issue where the bezier curve used to be deactivated if 3 points
with the same value were following each other.
See issue #73.
move number generation in separate method
add Segment control to select Bezier or straight curve.
fix position of segment for iPhone 4
cleanup
Merge pull request #76 from skywinder/sampleImprovments

Add segment to select Bezier or straight line on sample app
Fixed issue #73 and labels Y axis height

- The issue with bezier curves should now be totally fixed.
- The height of the labels on the Y-axis has been increased to make
sure the could display all the text.
Merge pull request #78 from Boris-Em/pr/76

Fixed issue #73 and labels Y axis height