Require a space between the command and its arguments (if it has any)

[connorkuehl]

This will require some changes to the regexps used to determine if a message is a command.

This might also ripple out to some test cases in router_test.go since some of the assertions were made assuming that the space isn't variable width.

If a command has optional args then a space is not required unless they are present.

command	requires args	has optional args
announce	✔️
karma	✔️
top		✔️
bot		✔️