Fix display of correct antecedent value in UI
Modify default values for floating base robots

Modify default values for floating base robots on creation of robot.
The parameters effected are base velocity, base acceleration, gravity
vector, Z transformation matrix.
Modify UI in new robot creation

During new robot creation, modify to make base parameters checkbox state
depend on floating base checkbox.
Minor modifications
Minor modification

Modify to update joint parameters based on `sigma` value.