Issue I460 [enhancement,example,resolved] Updated gauss_law example. This is based on the totalcharge example in 8.0.0/SL but rewritten in Lua and extended (e.g. new field energy calculation). It uses new Lua simionx.FieldAnalysis and simionx.Integration libraries. Implemented in 8.0.4-TEST21 (Lua version requires 8.1 early access mode)