Fixup - Reactive Power

In AC_STATUS_3, Martin Perlot noticed some verbiage which is inconsistent with the usual intent. Reactive Power is given as a "int16", with an offset
of 768. To be consistent with other, similar data items, it is proposed to replace the description with:

Date Type: uint16
Precision = 1 VAr
Value range = -32000 to +33530 VAr
0 = -32000 VAr, 32000 (7D00h) = 0 VAr
Negative values are “lagging”, positive values are “leading”.