Allow to get EC chunk by rule idx only #348
Description
See #345 (comment), rule/part is good for policer, but suboptimal for regular GET in case there was some change in netmap and part are placed suboptimally. Unlike with REP where a shift by 1 in node list is unnoticeable in most cases, with EC this means 12 failures for 12 tries to get a part in 12+4 scenario. The proposal is to allow to GET whatever part node has by rule only and leverage that in node. Additional testing can be helpful, but protocol-wise it's a rather simple thing.