Add --version option to ghc-events CLI

[BinderDavid]

Output in the usage help:

david@Davids-MacBook-Air ghc-events % ghc-events
ghc-events --help:                        Display this help.
ghc-events --version                      Print the version of ghc-events.
ghc-events inc <file>:                    Pretty print an event log incrementally
ghc-events inc force <file>:              Pretty print an event log incrementally. Retry on incomplete input (aka 'tail -f').
ghc-events show <file>:                   Pretty print an event log.
ghc-events show threads <file>:           Pretty print an event log, ordered by threads.
ghc-events show caps <file>:              Pretty print an event log, ordered by capabilities.
ghc-events merge <out> <in1> <in2>:       Merge two event logs.
ghc-events sparks-csv <file>:             Print spark information in CSV.
ghc-events validate threads <file>:       Validate thread states.
ghc-events validate threadpool <file>:    Validate thread pool state.
ghc-events validate threadrun <file>:     Validate thread running state.
ghc-events validate tasks <file>:         Validate task states.
ghc-events validate sparks <file>:        Validate spark thread states.
ghc-events simulate threads <file>:       Simulate thread states.
ghc-events simulate threadpool <file>:    Simulate thread pool state.
ghc-events simulate threadrun <file>:     Simulate thread running state.
ghc-events simulate tasks <file>:         Simulate task states.
ghc-events simulate sparks <file>:        Simulate spark thread states.
ghc-events profile threads <file>:        Profile thread states.
ghc-events profile sparks <file>:         Profile spark thread states.
Unrecognized command

Invocation of the command:

david@Davids-MacBook-Air ghc-events % ghc-events --version
ghc-events version: 0.19.0.1

[Mikolaj]

If nobody objects I'm going to merge.