Add command start time to preexec hook.

[rcaloras]

Since commands are messaged post execution and not pre, the actual time the command is executed can be far off. Add a command start time variable to the preexec hook to capture this.

[kootenpv]

Sounds great, can't believe I've only wanted this so much later, but I'm wondering if this has not been forgotten ^_^?

[rcaloras]

Not forgotten 👍 Just haven't gotten around to it. Feel free to submit a PR! I can do the server side once the client is sending this additional data.