- move environment marker always at start of output
- use single char logging level representation
- skip support for parallel runs
- rework parallel run to collect output per env, and also collect
logging lines, fix logging timestamps by materializing the log messages
when they are emited (collect the resulting output, instead replaying
the log records at a later stage)
- support for the -c file to specify tox configuration file at custom
path
- fix PEP-517 implementation by implementing a new type hinted PEP-517
frontend/backend interface
- add a executor for PEP-517 communication that starts up just one
process and then reuses that one process for all subsequent messages,
this also collects stdout/stderr for executed commands
- introduce async executor for the commands (alongside the current sync)
- add prefix to threads to ease of identification in debugging
Signed-off-by: Bernát Gábor <bgabor8@bloomberg.net>