Add native transformations for basic arithmetic with numeric and dateTime

[Seddryck]

It should be possible to perform basic arithmetic with native transformations:

• numeric-to-increment : add 1 to the current value
• numeric-to-add(incr) : add incr to the current value
• numeric-to-add(incr, times) : add incr to the current value several times. If times is zero, return current value.
• numeric-to-multiply(factor) : multiply the current value by factor
• numeric-to-invert : invert the current value (equivalent to 1/current value)
• dateTime-to-add(ts) : add ts (a timeSpan) to the current value
• dateTime-to-add(ts, times) : add ts (a timeSpan) to the current value several times. If times is zero, return current value.

[Seddryck]

Beta available at 1.21.0-beta0336 or at https://ci.appveyor.com/project/Seddryck/nbi/builds/27259640/artifacts