#163 Export large dataset in svg format

[michael michaud]

Currently, the export function fails silently for dataset over 10 000 features.

1 - put a higher limit (eventualy for 1.5.2 release)
2 - remove the limit and open a dialog box if the dataset is over 100 000 features
"Due to the important number of objects, the generated SVG file will have an important size and the process may be long (several minutes).
Do you want to continue?"

[michael michaud]

Fixed in r2845