new pretty printer

added usability label

Based on serialization code in !1000 (merged). Needs rebase once !1000 (merged) is merged.

mentioned in merge request !1026 (merged)

assigned to @pspacek

@pspacek I have to re-review this once rebased, this is too confusing

changed milestone to %5.2.0

mentioned in merge request !1000 (merged)

added 313 commits

• 1e00c1e9...43b40577 - 272 commits from branch master
• 4d6bf767 - map: use control sockets instead of pipe from parent process
• f38b02de - new serialization method krprint.serialize_lua
• e6240798 - krprint.serialize_lua: rename function parameter to on_unpresentable
• 6e7a79a8 - daemon: always listen on control socket, even in interactive mode
• 677aa078 - tests: improve process cleanup after config tests
• 83b93637 - tests: adapt config tests to new map()
• 9b86f69d - map: stricter argument checking
• ace843e3 - kluautil: table pack and unpack
• be3ff8e9 - map: input command validation
• cdeaddc9 - map: rework result handling
• 6fcb3ae6 - map: logging for weird responses
• d556df13 - daf: adapt to changes in map result handling
• 034709b3 - tests: limit number of iterations for krprint.serialize_lua to please CI
• 49772526 - kluautil: remove hard depedency on lua-cqueues
• 5df0d184 - tests: detect missing environment variable TEST_FILE
• 966076a1 - map: thorough error checking on control socket operations
• 9eb440ec - map: prevent crash on unrepresentable responses
• 6246d3a3 - map: disallow commands with \n
• 5804ac01 - map: tests
• 820de0bc - gitignore: add missing files created by kresd when executed in worktree
• eee60640 - kluautil.list_dir: make it portable to non-Linux
• 6b0fdf81 - systemd: control socket cleanup on exit
• dc650754 - map: document internal use
• 824c244d - prometheus: run on all instances
• 682a566a - http: adapt Prometheus to changes in map()
• 99e89bd6 - doc: document new command buffering scheme
• 6460a003 - worker: migrate worker.id to string
• 404b2cb9 - graphite: adapt to to changes in map()
• 3141914d - NEWS: cleanup incompatible changes
• 3555da10 - tests: fixes for control socket tests
• 6aa91740 - tests: control socket test improvements
• 34a81d49 - table_print: fix printing tables with key = false
• 106282ec - table_print: sort numbers by their value instead of lexicographic representation
• eb2de352 - krprint: reuse serialization infrastructure for pretty-printer
• 3be2540b - krprint: order keys while pretty-printing tables
• fe886364 - krprint: support pretty-printing functions
• 240c6358 - krprint: feature parity between old table_print and new pretty printer
• 3af493da - replace sandbox table_print with new pretty printer
• 7f4ce382 - table_print: print multiple values
• eee7f13a - tty: do not print extra newline after empty messages
• 7545607c - krprint: allow tab and newline in pretty printer

Compare with previous version

resolved all threads

unassigned @pspacek

unmarked as a Work In Progress

I've fixed issues found in previous review, fixed couple additional nits and rebased the whole thing on top of !1000 (merged). Should be good for review. Once MR!1000 is fixed I will rebase it once again.