Wrap Rounding Menu Functions for Transient Help

[kickingvegas]

Wrap Calc functions used by Rounding menu.

Preliminary function inventory:

• [ ] casual-rounding.el: ("r" "Round" calc-round :transient nil)
• [ ] casual-rounding.el: ("f" "Floor" calc-floor :transient nil)
• [ ] casual-rounding.el: ("c" "Ceiling" calc-ceiling :transient nil)
• [ ] casual-rounding.el: ("t" "Truncate" calc-trunc :transient nil)]