#107 Overwritting Baseline changes BaselineX costs

[Nick Faregran]

Tested in versión 1.5.9

1. Generate a Project. Add any tasks, resources, etc.
2. Save as Baseline
3. Save as Baseline1
4. Go to Costs view, prepare it to see Cost, Baseline Cost and Baseline1 Cost
5. Change Project, getting new costs. E.g., changing resource costs, adding new resources to task, etc.
6. Save as Baseline (both cleaning first of directly overwritting it)
7. Baseline1 cost is changed too...

So, baseline1 is invalidated and unuseful.