RVI Generic indicator for MT4

This is Mladen's Rvi generic updated for the new mt4.

Mladen's explanation::

I would just like to explain why "generic" in name : I did not use the "default" indicator that is provided by metatrader but am using a version that allows different period of values and signals smoothing. Smoothing used both for values and signal is the triangular moving average (the "regular" triangular moving average not the centered one, so there is no recalculation whatsoever) and is set by default to be the same as the built in indicator but also allows you to experiment with different smoothing lengths.