commands that affect the REPL state

[cgrand]

for example changing ns or setting print limits affects the command.
Related to #7 and #17.

They can't be sent on the user connection because it's hard to determine a safe point in the input stream for the client to send them.

So somehow they must be queued until the target REPL reaches a safe point (in the R.E.P. loop) to process them.

[cgrand]

As of 7fbecaa such "safe points" do exist.
Actions to be performed on the main thread are queued.
Right before prompt the queue is checked, if present the first item is executed and the prompt printed. Then comes reading (or rather seeking that is when the repl consumes top level blanks (or comments) until it finds a char that may be the start of a form). If while the REPL seeks there's something in the queue, then the seek aborts and we loop back to the prompt. Thus each queued action is going to trigger a prompt (not committing to this 1:1 behavior atm).