* Added asynchronous logging library
Did some rudimentary testing, might need more for safety.
Fixes#316 at least in part
* Included missing stdbool include
* Added console logging (in addition to file logging)
* Force a file flush at every write
This might be useful if we want to analyze the cause of a crash, if we
don't flush the file, one to several log lines might be missing.
* Added default log settings for release and debug versions
* Added LOG_*F formattable logging functions
* Allow the main thread to close the logger
Or LS will keep on logging from a detached thread.
* Empty the logger queue on thread exit.
This should remove the possibility of losing messages on exit.
* Add timestamps to logs and avoid double newlines
* Put the log file in XDG_DATA_DIR/libresplit
* Default LogLevel at Warns + Errors
Debug LogLevel stays at "everything"
* Bunch'o'statics
* Move prctl to the beginning of the logging thread code
* Add run history feature
* Added error handling, forgot to handle error
* Run clang-format
* Don't ls_run_save on reset if run finishes
* Save split segment time
* Reworked split structure, better handle skipped splits
