Change the default starting values for pressure when the user specifies any two-phase related boundary conditions

[fwitte]

In case the user applies

• a Desuperheater,
• a Condenser,
• a Drum,
• a DropletSeparator

the pressure values at the hot side inlet and outlet should be forced to be well within two-phase region, no matter what fluid is used.

Furthermore, when specifying

• x or
• Td_bp

while not specifying a second boundary condition on the same connection (i.e. the pressure is still a variable), then the starting value for the pressure should be modified to be within two-phase region as well.