digitizing SVG icons

This tries to bring more homogeneity with previous changes in layer icons.

See:
![image](https://f.cloud.github.com/assets/127259/2107978/11602ed2-8fd7-11e3-8c44-438137def278.png)
new icons are on the second row.

for points:
![image](https://f.cloud.github.com/assets/127259/2107988/50ffecf8-8fd7-11e3-83f4-ab66208d271d.png)
and lines:
![image](https://f.cloud.github.com/assets/127259/2107990/682a5062-8fd7-11e3-8bb5-b5d64d7ad36f.png)

I have change the new to be a plus. But this can be easily changed to a star as for the layers:
![image](https://f.cloud.github.com/assets/127259/2107992/88631404-8fd7-11e3-86a5-c3aa9f895026.png)

What do you think?