Faster slotmap builder for all-sided sidedInventoryAdapter
store the field as a static.

a large part of the cost of using this class was re-initing the fMap. we use this "allot" (one for every attached inventory slot for every pipe, every few ticks)
because using math.round() is just too slow.

(2% decrease in cpu from transport.moveSolids() )
Because a ServerRouter already knows what side it is on ...
add a nullCheck when getting the adjacent routers.

possibly a check in the main loop missed also, but havn't seen an NPE
error from that point.

fixes #533
Cleanup
Merge remote-tracking branch 'lp-dev/Dev' into dev