Fixes siemens_coefficent not affecting shock damage

Currently, siemens_coefficent has no effect unless it is 0. This meant that the siemens_coefficent of clothing was not being used, and in particular, budget insulated gloves were useless.

This also cleans up electrocute_act(), and allows the option of electrocuting specific defence zones.
I didn't ment your commit changed that, i ment IIRC it was removed some time ago.
i am aware the coeff was not very well implemented, but look at how the bodyparts covered are checked.
suits like certain vox space suits, cult robes, bomb suits etc cover the entire body when worn with their respective helmet/hat, which all have a coeff of 0, making you immune to stuns.
this is not a problem of your commit but more a problem with a coeff of 0.
instead of finding all those items, would you consider adding max(siemens_coefficient, 0.3) so atleast some agony passes through ?