v2.2.2.1 wallet update

While work is also done on the switch to BTC codebase v0.17, we haven't forgotten about the current version of the wallet, already available for our community. This update is another set of changes & improvements targeting better stability and user experience - after careful revision, code was added to slightly alter the speed of Enigma transaction handling, as well as some network buffer tracking/shaping. Motivation was to fix the d/c storm issue associated with Enigma transactions. The issue is not (and was not) reproducible on devnet or testnet with relatively small number of nodes - hard to say this is the final solution without testing it "in the wild" as the problem seems to be large network and/or bandwidth related; we would require most of our users to also run testnet nodes. That being said, we are also looking into putting in place a permanent testnet, where issues like this can be tested properly and will provide us with a better place to catch more errors before they hit livenet.

Note: To isolate the send/receive mechanics from previous client versions that have the issue, Enigma v1.2 is not backwards compatible."

Changelog:

introduced a small delay in processing enigma onion layers & relaying messages
added a delay to socket read when receive buffer approaching full to allow time for processing and relaying messages in the main thread
bumped client version to 2.2.2.1
bumped Enigma engine version to 1.2