Remove some unused fields and re-organize other ones. In particular: * Update the parameters of `ndpi_ssl_version2str()` function * Zattoo, Thunder: these timestamps aren't really used. * Ftp/mail: these protocols are dissected only over TCP. * Attention must be paid to TLS.Bittorrent flows to avoid invalid read/write to `flow->protos.bittorrent.hash` field. This is the last(?) commit of a long series (see 22241a1d, 227e586e, 730c2360, a8ffcd8b) aiming to reduce library memory consumption. Before, at nDPI 4.0 (more precisly, at a6b10cf7, because memory stats were wrong until that commit): ``` nDPI Memory statistics: nDPI Memory (once): 221.15 KB Flow Memory (per flow): 2.94 KB ``` Now: ``` nDPI Memory statistics: nDPI Memory (once): 231.71 KB Flow Memory (per flow): 1008 B <--------- ``` i.e. memory usage per flow has been reduced by 66%, dropping below the psychological threshold of 1 KB. To further reduce this value, we probably need to look into #1279: let's fight this battle another day.