* schema for sending files
* send file "invitation"
* receive file "invitation"
* send/receive file flow (with stubs)
* update simplexmq
* send and receive the file (WIP - only the first chunk)
* sending and receiving file works (but it is slow)
* use correct terminal output for file sending/receiving
* improve file transfer, support cancellation
* command to show file transfer status and progress
* file transfer tests
* resume file transfer on restart (WIP)
* stabilize test of recipient cancelling file transfer
* trying to improve file transfer on restart
* update SMP block size and file chunk size
* acquire agent lock before chat lock to test whether it avoids deadlock
* fix resuming sending file on client restart
* manual message ACK (prevents losing messages between agent and chat client and stabilizes resuming file reception after restart)
* do NOT send file chunk after receiving it before it is appended to the file
* update file chunk size for SMP block size 8192 (set in smpDefaultConfig)
* save received files to ~/Downloads folder by default; create empty file when file is accepted
* keep file handle used to create empty file
* check message integrity
* fix trying to resume sending file when it was not yet accepted
* fix subscribing to pending connections on start
* update simplexmq (fixes smp-server syntax parser)
