[Planner] Cost calculations

[Waldemar Augustyn <waldemar nxp com>]

I have just noticed, Planner's cost calculation is not quite right.  It 
appears, it misinterprets the resource "units" value. I thought the 
"units" figure is really the percentage of time a resource is expected 
(allowed) to work on a task.  The default is 100, which I think should 
be labeled with a %.

Here is what happens:

A  Task takes 3 days to finish.  There is one resource allocated to it 
at 50% time and 45 cost.  Planner properly calculates the task to take 
six days (because of 50% resource), but the cost is calculated at 540.   
I would think, it should be 3*8*45= 1080  (three days * 8 hours * 45 
$/hour).  Or, perhaps, 6*4*45=1080 (six days * 4 hours * 45 $/h).

Same thing with another task.  It takes 5 days to finish, the allocated 
resource works 5% of time at cost of 30.  Planner properly calculates 
the task to take 100 days to finish, but the cost is calculated at 60.  
I would think, it should be 5*8*30=1200.  Or,  100*(8/20)*30=1200.

I am using version 0.11.